The Asia policy of the 10-month-old Reagan administration is getting mixed marks from noncommunist Southeast Asian governments. After disappointment over what was seen as vacillation by the Carter administration, many of the region's leaders appreciate the reemphasized US military and economic commitments to countries like Thailand and the Philippines.
But, as elsewhere in the world, there is a desire for closer ''consultations'' to avoid sudden unexpected shifts of US policy. And there is disquiet on issues such as these:
* Concern that Washington might sacrifice Southeast Asian interests to its global goal of using China against the Soviet Union. The question for some is whether the US will help build up China economically, perhaps even with arms sales, to the point where Peking threatens its southern neighbors.
* Concern that the ''free enterprise'' philosopy of President Reagan has put Southeast Asia and the US in opposite corners on such issues as foreign aid, law of the sea, and free access to the markets of developed countries for exports from developing countries.
* Uneasiness that the Reagan administration, in its eagerness to build a rapid deployment force for the Mideast, might push harder for base rights in Southeast Asia, thus forcing nations there to drop their protestations of nonalignment.
Southeast Asian governments are wary of growing Soviet power. But many are reluctant to invite a renewed cold war in the region by joining hands with the United States in a full-fledged anti-Soviet alliance.
The nature of these concerns was evident both in public, and behind the scenes at a conference Nov. 11 to 13 on the Association of Southeast Asian Nations (ASEAN) at the Fletcher School of Law and Diplomacy, at Tufts University in Medford, Mass.
Officials and journalists from ASEAN members Thailand, the Philippines, Malaysia, Singapore, and Indonesia met with US government officials and academics prominent in Southeast Asian affairs.
Thailand, though conscious of Peking as a long-term problem, welcomes China's support as a powerful deterrent to an attack by Vietnam across the Thai-Cambodian border.
But Malaysia's colorful foreign minister, Tan Sri Ghazalie Shafie, dramatically chastised China for continued support of guerrilla insurgents in Malaysia and elsewhere despite Peking's protestations of friendship and moderation.
The minister jabbed his fingers to the ceiling for emphasis, as he sarcastically declared China ''is serving rotten fish in sweet and sour sauce.''
In Malaysia and Indonesia, non-Chinese Muslim majorities are sometimes fearful that China will use ethnic Chinese minorities as guerrilla ''fifth columns.''
A concern is that the US will tilt too far toward China by supporting a Chinese policy of ''bleeding'' Vietnam in Cambodia and restoring pro-Peking Khmer Rouge rule there. Some ASEAN officials want the US to press ASEAN's call for a compromise in Cambodia more vigorously upon Peking.
One reason for this is Malaysian and Indonesian thinking that Vietnam's strength should be preserved as a future protective buffer against China.
Recognizing these sensitivities, Assistant Secretary of State for East Asian and Pacific Affairs John Holdridge told the conference that the US is not out to ''bleed'' Vietnam. To the concern that the US might tilt to China, he declared, ''Our relationship to ASEAN is second to none.''
Mr. Holdridge declared the Reagan administration would consider only defensive weapons and technology, and that on a case-by-case basis after consultation with both ASEAN and the US Congress. Even so, he added, the Washington-Peking dispute over Taiwan casts a shadow over such sales.
''Mr. Holdridge's comments show the administration has taken a step to quiet ASEAN concerns,'' one Southeast Asian diplomat noted.
Discomfort with a variety of Reagan ''free enterprise'' policies was evident even though Foreign Minister Ghazali Shafie declared commitment to free enterprise was a crucial aspect of ASEAN policies.
ASEAN nations may be forced to oppose the US or be isolated in bodies like the United Nations if they support US policies, noted Indonesia's deputy permanent representative at the UN, Ambassador Hasim Djalal.
He politely but firmly cited as problems for ASEAN the US opposition to a draft law of the sea treaty, its restriction of foreign commodity imports, and its policies concerning the North-South dialogue, outer space, and disarmament.
The administration's opposition to a law of the sea draft treaty is particularly unwelcome in Indonesia, since, according to Indonesians, the US view would bar Indonesian jurisdiction of expanses of water separating Indonesia's islands.
The longterm concern that Washington might try to lead Southeast Asia back into cold war was spotlighted by comments to the conference from Richard Solomon , a Rand Corporation Asia expert who served on the National Security Council during both Nixon and Ford administrations.
Mr. Solomon said ASEAN countries must reconsider whether neutrality is still ''a viable strategy given Soviet growth.'' ASEAN must be aware of how its interests are affected by events in other parts of the world including the Middle East, he noted.