Summary service helps subscribers keep up with new business books

''There's an awful lot of information we can live without,'' says Harold Longman.

Mr. Longman's company, Soundview Executive Book Summaries in Darien, Conn., provides four-page summaries of what he considers to be the most important and interesting books on business.

He condenses books with such alluring titles as ''Secrets of a Corporate Headhunter,'' ''The Art of Japanese Management,'' and ''The New Taxpayers' Counterattack.'' He also explains economic theory when capsulizing such books as ''Successful Techniques for Higher Profits.''

''They all may have intriguing titles, but a lot of them tell you nothing new ,'' Mr. Longman notes.

There are more than 1,000 business books published each year; Mr. Longman picks 30 to condense. He has some help in picking books. A committee, consisting of two retired businessmen, a business professor, and a former book publisher, selects the books on the basis of their value to aspiring or innovative business people.

For $67 a year, customers receive the 30 summaries and several bonus issues containing interviews with prominent authors. Currently there are 12,000 subscribers, about enough to break even.

Longman says he believes his product has a potential market of 50,000 to 75, 000 copies.

Formerly a vice-president of Macmillan Inc., a book publishing company, Longman launched his firm three years ago.

Longman's company is based on his conviction that a great part of the trouble with American business is bad management. One reason for poor management, he says, is that business people have become so specialized that they miss the ''forest for the trees.'' Longman contends a broader knowledge of the entire business community would help remedy many problems.

Yet the market is so flooded with information that many people are unable to keep pace with the latest developments in business. By reading his summaries, executives can more easily keep abreast of the most effective business tactics, Longman says.

Connie LeBeau agrees. She started her interior-decorating business with help from Longman's summaries.

''Both my husband and I are very pleased with the summaries,'' says Mrs. LeBeau, a subscriber from Birmingham, Mich. One summary in particular, ''How to Be Financially Successful by Owning Your Own Business,'' provided Mrs. LeBeau with practical advice for starting her business.

The LeBeaus most appreciate the time savings the summaries afford. ''We have a family to raise, and we just don't have time to sift through every business book we should be reading,'' Mrs. LeBeau says.

Philip Randolph, a Merrill Lynch institutional salesman in Rosemont, Pa., says the summaries only mildly affect his business. But he recommends them for the breadth of information they provide.

Part of the appeal of the Soundview summaries their uniqueness, says Andrew Baier, marketing manager for Dow Jones-Irwin Books, a publisher of business books. Mr. Baier says the summaries are much more comprehensive than ordinary reviews.

''We've been enormously fussy about clear communication,'' says Longman. Once a book is chosen, he estimates that it takes a total of three months at an expense of $2,000 to wrestle a 300-page book down to four pages. ''We make no attempt at being literary,'' Longman, an author of children's books, adds.

But how much of the value of a book can a summary retain? According to Longman, the whole point is not to lose the meaning, but to cut out unnecessary information. ''What has to be sacrificed are details you think are unimportant, '' such as financial computations and case studies, he says.

Is this a retirement hobby for him?

''I've been working at it seven days a week, and that's hardly retirement,'' jokes Longman, who coordinates a full-time staff of eight and many outside writers. He says he eventually hopes to branch out into science books and other ''overspecialized'' fields.