After two hours of debate, the Senate ovewhelmingly confirmed yesterday the appointment of industrialist G. William Miller to a four-year term as chairman of the Federal Reserve Board.

The only "no" called out in the voice vote was that of Banking Committee Chairman William Proxmire (D-Wis.).

Before the vote Proxmire told his colleagues that Miller, the 52-year-old chairman of Textron Inc., is unqualified by training, education or experience to become the nation's top banker.

Proxmire said Miller enters office under investigation by the Securities and Exchange Commission and under a potentially damaging cloud of suspicion that could place him in civil or criminal jeopardy and undermine the independence of the Federal Reserve.

The SEC is studying a $2.9 million payment by a Textron subsidiary, Bell Helicopter, to an Iranian company which was controlled by Iran's air force commander-in-chief.

Proxmire was a minority of one when the Banking Committee voted 14 to one on Thursday to recommend Miller's confirmation, concluding an extensive examination of the Bell payment by he committee.

All other senators who spoke during the debate yesterday said they thought Miller was fully qualified for the Fd position. Sen. Adlai Stevenson Jr. (D-Ill.) said Miller's "reputation is without blemish . . .

Miller, who succeeds Arthur Burns, must begin dealing with the problems of how to expand the economy and curb unemployment while restraining inflation and bolstering the sharply declining value of the dollar.

The dollar rose slightly yesterday and Thursday against the German mark and Swiss franc after setting record lows against the two currencies Wednesday.

The dollar's slide could lead to an unstable international monetary system, add to inflation by raising the price of U.S. imports and might prompt oil-producing nations, which are paid in dollars, to boost petroleum prices to offset their loss in real income as the worth of the dollar shrinks.

The Banking Committee's investigation involved allegations that the Bell payment was, in effect, a bribe to Iran's air force chief to win a $500 million helicopter sale to Iran in 1973.

Proxmire said that Miller should have known that the Iranian firm which helped Bell Helicopter obtain the sale was secretly owned by the late Gen. Mohammed Khatami.

But Miller denied knowing about Khatami's alleged ownership of Air Taxi Inc. He told the committee that Bell's $2.95 million payment to Air Taxi was a settlement of a sales commission claim, not a bribe.

Miller insisted at his confirmation hearing that he has done nothing improper or illegal as head of Textron. Members of the Banking Committee said no evidence surfaced linking Miller to any wrongdoing.

President Carter named Miller to a four-year term as chairman, but he could serve on the board as a member for another 10 years after that.

In his initial confirmation hearing, Miller pledged to maintain the traditional independence of the Federal Reserve from both the president and Congress.