Rep. Richard Kelly of Florida resigned in tears from the conference of all House Republicans yesterday to avoid the pain of a vote to expel him for alleged involvement in the Abscam bribery operation.

The action is largely symbolic, Kelly will remain a member of the House and retain his committee assignments. But House Republicans no longer accept him as a party member. He will receive no more campaign contributions from the congressional campaign committee.

Moreover, House Republicans can claim they acted faster than Democrats to clean up after Abscam, and they can campaign against it as a wholly Democratic scandal.

Kelly has admitted accepting $25,000 from undercover FBI agents who allegedly gave money to several House members during an investigation of corruption. But Kelly contended he took the money only to protect an investigation he was conducting on his own.

Because no charges have been brought against any of of the members and only now is the evidence to go to a grand jury, several Republicans at the closed conference yesterday opposed action against Kelly on grounds that he was being denied due process.

Rep. Henry Hyde of Illinois described as a "lynching" the resolution approved by party leaders and the House Republican Policy Committee late Wednesday and put before the conference at 9 a.m. yesterday.

The resolution would have expelled Kelly from the conference and instructed the Republican Congressional Campaign Committee to give him no more contributions. After Kelly resigned, campaign chairman Guy Vander Jagt of Michigan said he felt no formal action to cut off aid would be needed because Kelly was no longer a Republican as far as his committee was concerned.

It apparently is the first time in more than half a century that House Republicans have pushed a member out of the party organization.

Kelly appeared at the closed metting yesterday. Reportedly he did not try to argue his case on the merits, but contended that he had unfairly been denied a chance to make his case. Party leaders approved the resolution without informing him that they were meeting, Kelly said, and he learned about it Wednesday evening after the fact.

One member at the meeting said that there was "substantial" opposition to the attempt to drum Kelly out of the party, but that it appeared the expulsion resolution would have been approved if put to a vote.

Several members suggested that Kelly resign from the conference to avoid the unpleasant task of voting. Just before the issue was to be put to a vote, Rep. Robert Bauman of Maryland pleaded with Kelly to resign voluntarily from the conference. Kelly finally agreed, in tears, several members said.

To the argument that Kelly was denied fair treatment, Republican leaders replied that his acceptance of the money is "perceived" as a breach of public trust and that the integrity of the House was at stake.

Demands that Republicans discipline Kelly without waiting to see if he is indicted and convicted of a criminal offense were voiced in considerable part by freshmen members. They won some seats in 1978 because of the odor of Democratic corruption and see Abscam as a great issue to run against this year.

Speaker Thomas P. O'Neill (D-Mass.) said, when told of the Republicans' action: "They never heard of due process. Half a dozen young Republicans have more clout around here than a half a dozen young Republicans ever did before." O'Neill has resisted suggestions that Democrats allegedly involved in Abscam be disciplined, because no criminal charges have been brought.