The Maryland House of Delegates, in what is believed to be the first such action in the legislature's history, is expected to vote next week whether to formally consider disciplining Prince George's Del. Francis J. Santangelo for alleged ethics violations, according to sources.

Following ethics procedures enacted two years ago, the House is expected to vote on a finding by the legislature's Ethics Committee that Santangelo created "a question of substantial conflict of interest" by allegedly using his influence to win state contracts for a "big band" promotion company in which he had a financial interest, sources said.

The vote on the opening day of the General Assembly's 1981 session Jan. 14 would determine whether a special House investigative committee would be named to consider the case against Santangelo and recommended House action. The committee could recommend that the House take no action, or, at the most, that Santangelo be formally censured.

The Ethics Committee's finding came on a secret vote after almost a year of consideration of Santangelo's case and three days of closed-door hearings in September, sources said. The committee then sent a letter this fall to House Speaker Benjamin L. Cardin requesting that he introduce a resolution to create the committee in the upcoming session.

Santangelo, 61, a three-term legislator from Landover, said yesterday he had received a copy of the Ethics Committee's letter to Cardin, but refused to comment further. He has denied the allegations.

Cardin is expected to introduce the resolution and bring it to a vote on the session's opening day, although he is not required to act that quickly, sources said.

Legislative officials said the House vote apparently would be the first instance in legislative history in which the General Assembly considered action against one of its own members for ethics violations.

In the past, the legislature has tended to avoid or ignore the misdeeds of its members, who have included one House speaker, A. Gordon Boone, who served jail time in the 1960s for political corruption, and a delegate, James A. Scott, who was arrested on drug-related charges in the midst of a legislative session in the early '70s.

The procedures that are being used in Santangelo's case went into effect in 1970 and were enacted by the legislature as part of an ethnics reform package that year.

The charges against Santagelo surfaced in a Prince George's County grand jury investigation in early 1979. At that time Maryland Attorney General Stephen H. Sachs asked the grand jury to look into allegations that Santangelo used his office to land state contracts for Dana Promotions Inc. to stage up to nine dances at the state-run Ocean City Convention Hall.

According to the allegations against Santangelo, the mustachioed insurance broker tried to win the contract for Dana in 1976 by asking an aide to then-Gov. Marvin Mandel and a state senator from the Eastern Shore to use their influence with members of the state commission responsible for awarding the Ocean City contract. The commission awarded Dana the contract the following year.

By the time Dana received the contract in 1977 Santangelo had obtained a financial interest in the New Carrollton-based promotion firm, although he failed to disclose that interest in his 1977 financial disclosure statement filed with Maryland's secretary of state. According to state law, legislators must dislose their "interests during the reporting period in corporations." This disclosure ommission by Santangelo was a focus of the later Ethics Committee probe.

Santangelo filed an admendment to his 1977 disclosure form listing his "profit-sharing" interest in Dana during the grand jury probe in 1979. The grand jury cleared Santangelo in September 1979 and issued a report that criticized Sachs' office for requesting the investigation, then failing to "follow through" on it, even as news reports detailed the grand jury's work on the case.

The Ethics Committee probe was initiated in January 1980 at the request of Cardin, who also sits on the committee. The committee, which is composed of four other delegates and five senators, discussed the issue in various closed meetings before holding the closed hearings last September. Santangelo and dozens of witneses, including several other Prince George's legislators, testified during the hearings, sources said.

If the Ethics Committee's recommendation is approved by the House vote, Cardin, as speaker, would appoint the members of a special committee, officials said. Several Ethics Committee members reportedly feel that the investigative committee should include the five delegates who have already heard the case of Ethics Committee members. The committee would receive the now-voluminous record of the case compiled by the Ethics Committee, and could then decide to hold its own hearings or simply use the Ethics Committee record, officials said.

The new state ethics law has no provisions for the amount of time a special committee would take to report bact to the House nor how, exactly, they would go about their work. House leaders are expected to press for a quick disposition of the case.

Cardin and Ethics Committee members said yesterday they would not discuss the Santangelo case or their actions on it.