Louis O. Giuffrida, director of the Federal Emergency Management Agency, and six top deputies yesterday defied subpoenas to testify before a House subcommittee, which heard allegations that Giuffrida had ordered aides to award $200,000 in noncompetitive contracts to an old Army friend.

In one of several allegations of fraud, favoritism and mismanagement detailed yesterday, two FEMA employes said they had been ordered to approve a proposal for Giuffrida's associate to computerize a data bank that already is computerized.

Giuffrida's refusal to appear under subpoena before the House Science and Technology subcommittee on investigations and oversight came after FEMA officials were assured by the panel's Republican members that they also would boycott the hearing.

Executives from two FEMA consulting firms that are under investigation by the Justice Department also defied subpoenas to testify. Spokesmen for the FEMA officials and the consultants said they believe that the subpoenas were not valid because a committee rule requires that any official hearing include a minority member.

Rep. Albert Gore Jr. (D-Tenn.), the subcommittee chairman, lashed out at the Republican members for "stonewalling" the investigation of alleged fraud and mismanagement at FEMA and for "protecting" the witnesses by informing them of the boycott.

"I would be embarrassed to allow myself to be used by the officials of a company charged with illegally spending taxpayers' funds," Gore said.

Current and former employes of FEMA, a six-year-old agency charged with emergency and disaster planning, testified that:

* A top Giuffrida aide, Frank Payne, ordered two subordinates to award the noncompetitive contracts to an Arlington firm headed by a man who attended Army War College with Giuffrida. The employes said Payne told them that Giuffrida wanted the contracts approved in one day, regardless of the merits, but that they refused and the contracts were never awarded.

* Triton Corp., a Washington consulting firm, billed FEMA $1,200 for Giuffrida and his wife to attend a "Salute to President Reagan" sponsored by the American Conservative Union and Young Americans for Freedom. Triton executives and former FEMA official Fred J. Villella and his wife also attended the $125-a-plate dinner in March.

The panel previously disclosed that Triton had billed the agency $2,000 for company officials to take the two FEMA officials and their wives to a fund-raising reception for the National Republican Club.

* FEMA officials transferred a contracting officer who questioned some of Triton's expenses. The agency then adopted an expedited system in which Triton's bills are paid before they are reviewed by the new contracting officer.

The Justice Department probe centers on allegations of improper billings in more than $7 million in FEMA contracts awarded to Triton and IMR Corp. of Arlington.

The battle over the subpoenas was touched off when the four Republicans on the 10-member subcommittee -- Reps. Joe Skeen (N.M.), Claudine Schneider (R.I.), Larry Winn Jr. (Kan.) and Alfred A. McCandless (Calif.) -- informed Gore Monday that they would not attend the hearing. The Democratic members had approved the subpoenas along party lines in October; the Republicans had forced Gore to cancel a hearing that month, charging that it was politically timed.

Skeen told Gore that "the Department of Justice investigation . . . should continue without compromise or disruption by the subcommittee." Gore noted, however, that Congress has a constitutional right to conduct hearings regardless of a criminal investigation.

FEMA spokesman James L. Holton said that top agency officials decided not to attend the hearing after Republican members told them there would not be a quorum. He said FEMA also is concerned about interfering with the Justice Department probe and that "we are not attempting to impede the [House] investigation or to cover anything up."

A Triton spokesman said company officials came to the hearing but left because there was no quorum. An attorney for IMR told Gore that the company's president could not appear because the Justice Department was questioning him about the same matters yesterday.

The White House counsel's office was informed of the FEMA officials' decision but did not provide advice, a White House spokesman said.

A House lawyer said yesterday that even if the hearing lacked a quorum, that does not excuse witnesses who were subpoenaed.

Gore said he intends to seek a contempt-of-Congress citation against the absent witnesses. However, Gore was elected to the Senate last month and will not be present when the new House convenes in January. As a practical matter, the contempt case probably will be dropped if the witnesses agree to testify in the future.

Gore said he expects the subcommittee to continue the probe next year and that the House Energy and Commerce subcommittee on oversight and investigations, headed by Rep. John D. Dingell (D-Mich.), also plans to pursue the case.

The FEMA officials who refused to testify are Giuffrida, Payne, deputy director Robert Morris, executive deputy director Gerald S. Martin, inspector general Robert C. Goffus, general counsel George Jett, congressional lobbyist Ron Eberhardt and the former No. 3 official, Villella.

Also refusing to testify were Triton officials Richard Salvatierra, Albert Ferri and John Smith, and IMR officials Ike Gibson, William Elsey and Paula Smith-Elsey, a former aide to Giuffrida.

Gore said that FEMA was involved in "a legalistic cover-up" and had refused the panel's latest request for agency documents. He said FEMA officials told his staff that they have been directed by the Justice Department to keep the records in a locked room.

Two FEMA employes told the panel that they felt pressured by a morning meeting in which general counsel Jett announced that they would not have legal representation if they agreed to testify. Spokesman Holton said there was "nothing that smacked of intimidation."

In other testimony, Frank Serio, vice president of Analytical Systems Engineering Corp. of Arlington, said he had talked with Giuffrida and Villella about his plans to seek FEMA contracts. Serio said that he considers Giuffrida a friend, but that "at no time" did Giuffrida offer to help him obtain funding for his unsolicited proposals to FEMA.

Serio said he offered to computerize FEMA's data bank of trainees in Emmitsburg, Md., because he mistakenly thought it was a manual system.

Two FEMA employes, Charles Turner and Jim Coyle, testified that Giuffrida aide Payne had ordered them to approve Serio's proposals quickly. They said Payne later called Giuffrida's office to report that he couldn't follow "orders" because of their objections.

Warren Rucker, a FEMA contracting officer, said he was taken off the Triton contract after questioning some of the firm's billings, and that his performance rating was lowered and his pay reduced. He said he considered this retribution for his criticism.

Spokesmen for FEMA and Triton said the firm was one of several contractors put on a "fast payment" system because of the agency's slowness in paying its bills, and that rejected expenses could be recovered later.

The Triton spokesman said the firm had charged FEMA for the Reagan banquet tickets through a bookkeeper's "misinterpretation" and that the $1,200 was later refunded to the government. Giuffrida did not know who paid for the tickets, according to Holton.