A key member of the Senate Intelligence Committee put the White House on notice yesterday that the panel does not have enough confidence in CIA Director William J. Casey's expertise and wants every effort made to give him a qualified deputy.

Sen. Richard G. Lugar (R-Ind.) said he and his fellow committee members were stunned by the abrupt announcement this week of CIA Deputy Director Bobby Ray Inman's resignation. Lugar called it "a rather traumatic situation" for those in Congress whose job it is to oversee the intelligence community and make sure it stays within proper bounds.

He made his remarks at a news conference that he frankly described as intended "to send some signals" to the White House about the gravity of the matter. Lugar made clear that the committee wants to be consulted before a successor to Inman is named.

"If this be meddling, so be it," Lugar declared.

Again and again, Lugar emphasized that it was Inman, not Casey, upon whom the committee has relied since President Reagan took office for expert advice and sound judgment on U. S. intelligence activities.

"It sounds as though you're saying you don't trust Bill Casey," one reporter told him.

The senator replied, "I wouldn't say that at all." He called Casey, who had served as chairman of President Reagan's election campaign, "a very able American who has the trust of the president."

Lugar, a former Navy intelligence briefing officer who served at the Pentagon with Inman years ago, added, however, that "there are simply complexities involved in the intelligence business that would take more years than Bill Casey has" left to understand.

"So," asked another reporter, "you're saying that Mr. Casey doesn't know enough for you to call him on the telephone" and ask for his expert opinion?

"That's right," Lugar replied.

Senate Intelligence Committee Chairman Barry Goldwater (R-Ariz.) was also upset on learning of Inman's decision to resign.

Goldwater said, however, that he regarded Casey as "a fine man, honest . . . a real spy when he was with the OSS Office of Strategic Services , a real guy with a dagger."

At that, Goldwater raised his hand, as though wielding a dagger, then added: "But we do it differently now and he is not a pro."

At his news conference, Lugar noted that Goldwater and others had hoped to see Inman appointed to the top job at CIA. He was named instead to the second spot, which he reluctantly agreed to take after serving as director of the National Security Agency. In any event, Lugar emphasized:

"Many of us voted for Casey and Inman as a package," meaning that they supported Casey because President Reagan wanted him and felt comfortable with him and Inman, a intelligence professional of 30 years, "because he knows more than anyone else what's going on."

Several times, Lugar suggested that the "system of checks and balances" that has been built up around the intelligence community since the congressional investigations of 1975-76 was at stake.

He said he had no quarrel with the CIA director's being "a political appointee" who the president could trust, but suggested that it was vital, in turn, for the deputy director to be an intelligence expert who Congress could trust.

Inman, 51, submitted his resignation to the White House on March 22 because, he has since said, he wants to start "a second career" in private industry and "get back to running something" himself.

"I was absolutely not hounded out," Inman declared. "Anyone in government who claims that is just building up his own ego. It was absolutely my initiative and my choice."

Lugar is chairman of the Intelligence subcommittee on analysis and production.