The General Accounting Office, the auditing arm of Congress, has found that seven of the 11 defense industry members of an advisory Pentagon task force "had a financial interest" in pursuing a proposed new policy for defense computer procurement bitterly opposed by the commercial data processing industry, Rep. Jack Brooks (D-Tex.) said at a hearing of his House Government Operations subcommittee yesterday.

Brooks did not name the seven members. The GAO declined to comment, but its boss, Comptroller General Charles A. Bowsher, is expected to disclose details of the investigation to the subcommittee today.

Several task force members, reached by reporters yesterday, said there was no impropriety.

The proposed procurement policy would establish a formal method for the armed forces to develop and acquire computer systems of their own design for critical military operations, rather than buying equipment from commercial manufacturers. Currently, the size of the annual market is estimated at $1 billion, but it is expected to grow to $38 billion by 1990.

The Pentagon had no immediate comment on any phase of the matter. Defense Secretary Caspar W. Weinberger yesterday notified the subcommittee that he had designated H. Mark Grove, assistant deputy undersecretary of defense for research and advanced technology, to testify before Brooks for the Pentagon and the Defense Science Board. Grove is executive secretary of the task force.

The longtime principal advocate of the controversial computer policy is Richard D. DeLauer, the Pentagon's fourth-ranking official as undersecretary for research and engineering.

DeLauer, who is Grove's boss, was a member of the Defense Science Board and chairman of the DSB's management panel before coming to the Pentagon in the spring of 1981 from TRW Inc., a leading military contracting firm of which he was an executive vice president and director.

When asked, John G. Weber, one of two TRW officials listed among the 11 task-force members as of August, 1981, told a reporter that he had no conflict of interest. He said he left the company in June.

Another task force member, Alan J. Roberts, vice president of Mitre Corp. in Bedford, Mass., said he could not understand the GAO's allegation. "Almost everybody I know who worked on that issue had no interest in the outcome," he said.

Task Force Chairman Thomas H. Crowley, executive director for computer technology at Bell Laboratories in Murray Hill, N.J., said he was "absolutely convinced there was no conflict of interest which had any impact on any of our decisions."

Crowley added that "I don't know any company in the country that does any defense business that doesn't have a financial stake in the outcome."

George H. Heilmeier of Texas Instruments Inc., asked if he had a conflict, said in Dallas that neither he nor his company had one. He said he had been on the Defense Science Board for 10 years, and, "I have never seen anyone vote their own special, selfish interest. I reject the inference that because a person works for a company that is in the computer business that individual is totally and hopelessly biased."

Federal law generally makes it an offense punishable by up to two years in prison and a $10,000 fine for a federal "special government employe" to participate "personally and substantially" in any matter in which his employer "has a financial interest," unless he discloses the interest and receives written dispensation. It is unclear whether members of the task force are considered such special employes.

DeLauer asked the board last August to organize the task force. The request developed out of Pentagon concern that "software" programs, which instruct computers--the "hardware"--what to do, were proliferating almost out of control and, at $6 billion a year, were too expensive.

In early 1981 DeLauer and other Pentagon officials began to press to implement a regulation, called "5000.5X," which would let the armed services acquire and develop their own data processing systems for weapons, command and control of military forces, intelligence activities and cryptology related to national security.

Witnesses for commercial computer companies and trade associations charged at yesterday's hearing before Brooks that the regulation is a device to get aerospace and other military contractors into the computer business at their expense.

A TRW spokesman said yesterday, however, that the company "has no plans in the next several years" to start making computers of the kind at issue.