President Carter's arms sales policy has "put our government in the worst of all worlds," Rep. Paul Findley (R-Ill.) charged yesterday at a House hearing where the State Department witness stumbled over the administration's new math for toting up its international weapons business.

Findley complained to Lucy W. Benson, undersecretary of state for security assistance, during a house International Relations subcommittee hearing that the case of the Navy frigates that Iran wanted to buy from the United States "makes the arms ceiling appear to be empty if not phoney."

First, said Findley, the Carter administration told the Shah of Iran last fall that he would have to buy the hull of the Navy FFG-7 frigates from some country other than the United States to help keep arms sales under the fiscal 1978 ceiling established by Carter.

As a result, Iran has been negotiating with the Netherlands and West Germany to build the frigate hulls. But this July, Findley said, the administration changed course by informing the shah it would sell the weaponry to Iran for the frigates and perhaps let American yards build the hulls after all.

Benson said that she didn't know the full details of the transaction but would supply them for the record.

The upshot of the frigate episode, Findley complains is that domestic shipbuilders are angry and U.S. allies are confused.

Two other members of the House subcommittee, Rep. Gerry E. Studds (D-Mass.) and Stephen J. Solarz (D-N.Y.), told Benson that the apparent shakiness of the shah's government in Iran is cause for concern because of all the modern American weapons that might fall into unfriendly hands if there is a change of power in that country.

Solarz said that he was specifically worried about the highly secret Airborne Warning and Control Systems (AWACS) aircraft that are destined to go to Iran, starting in 1981. Declaring his concern was serious, he then asked facetiously if the State Department: had made any arrangements "if and when the she should feel obliged to go into exile for him to fly out on one of the AWACS we sold him."

Benson replied that no such arrangements had been made and attributed the unrest in Iran to the reforms the shah was trying to make there, including more freedom for Iranian women.

The administration's figures for the past fiscal year came in for heavy criticism during the subcommittee hearing. Those figures show that total military sales and grants came to $13.7 billion in fiscal 1978, compared with $11.4 billion in fiscal 1977.

The administration has imposed an accounting system under which the sales of weapons to countries other than those in the North Atlantic Treaty Organization, Japan, Australia and New Zealand are subject to a ceiling.The target ceiling for 1978 was $8.5 billion, and 8 percent reduction from the fiscal 1977 figure, and one the administration says it achieved.

Subcommittee Chairman Lee H. Hamilton (D-Ind.) asked Benson what type of military construction projects were counted against the administration's weapons ceiling of $8.5 billion. Benson replied that the military part of an airbase would count against the ceiling but such related facilities as parking lots and family housing would not.

As she testified to that effect, Lt. Gen. Ernest Graves, the Pentagon arms sales director sitting beside her at the witness table, shook his head in disagreement. He corrected Benson by telling the committee that any type of military construction, including an airbase or a naval facility for warships, would not be counted against the administration's weapons ceiling.

This prompted Solarz to complain to Benson that the explanation "sounds as if it were drafted by the ghost of George Orwell, because at the same time total arms sales are going up, we claim they are going down."

"We are not trying to say more is less," Benson replied. "We are saying that in 1978 we did sell more arms altogether than in 1977. We are also saying" that the president's goal of reducing weapons sales to ceiling countries by 8 percent was achieved.

In a lengthy exchange with Hamilton, Benson said that the administration has not decided whether to strive for another reduction in arms sales in fiscal 1979. She said that the administration officials involved with arms sales are scheduled to meet on Oct. 17.

In other testimony, Benson and Graves made these points:

Airplanes for Taiwan. An administration task force is expected to decide within two weeks whether to recommend formally that 50 Northrop F5G fighters be sold to Taiwan. Graves said that Northrop would need to sell a "minimum" of 300 F5Gs to make development and production economically feasible.

Arms backlog. Graves said that as of Aug. 31 the U.S. government had orders for $43.5 billion in weapons to be delivered between now and 1986.

Arms for Egypt. Benson said that no formal request is pending but one is expected. She said that at one time Cairo wanted 800 armored personnel carriers but has not renewed that request.

Arms for Israel. The wish list for weaponry is still under review, with the F18L fighter plane in which the Israelis have shown a fresh interest.