President Bush yesterday dramatically restructured the President's Foreign Intelligence Advisory Board (PFIAB), naming former Texas senator John G. Tower as chairman, shrinking the membership from 15 to six and eliminating a number of prominent members appointed by then-President Ronald Reagan.

The shakeup in the board, which advises the president on intelligence operations, had been expected for several months, as Bush, a former CIA director, sought to create a smaller panel composed of people with greater expertise on intelligence.

Tower's nomination as secretary of defense was rejected by the Senate in 1989 after a bitter confirmation fight that included charges of drinking, womanizing and conflict-of-interest. His elevation to the chairmanship of the panel puts the former senator into a potentially influential role in the Bush administration.

Tower will succeed another Texas Republican, Anne L. Armstrong, as chairman.

The appointments announced yesterday underscore Bush's desire to have intelligence experts on the panel but could reopen debate about potential conflicts-of-interest arising from the use of outside consultants to oversee sensitive intelligence matters.

The other members are:

Lew Allen Jr., vice president of the California Institute of Technology and director of the Jet Propulsion Laboratory, and a former Air Force chief of staff as well as former National Security Agency (NSA) director from 1973 to 1977.

John M. Deutch, provost and Karl Taylor Compton Professor at the Massachusetts Institute of Technology and former undersecretary of energy during the Carter administration.

William G. Hyland, editor of Foreign Affairs magazine and former staff member and later deputy director of the National Security Council during the Nixon and Ford administrations.

Bobby Ray Inman, former deputy director of the CIA for the first two years of the Reagan administration and former director of the NSA, now a consultant in Austin, Tex.

William J. Perry, chairman and chief executive officer of Technology Strategies and Alliances in Menlo Park, Calif., and a former undersecretary of Defense during the Carter administration.

Among those not reappointed by Bush were former Senate majority leader Howard H. Baker Jr.; former defense secretary Caspar W. Weinberger; Jeane J. Kirkpatrick, former United Nations ambassador during the Reagan administration; Zbigniew Brzezinski, national security adviser during the Carter administration, and William French Smith, attorney general during the Reagan administration.

The board, which generally meets about every other month, has been moribund during Bush's time in office. Former secretary of state Henry A. Kissinger resigned his post last winter and Armstrong had indicated her desire to leave the panel.

"It was felt that a small number of people was the most efficient way for the board to carry out its duties," an administration official said yesterday.