Republican presidential nominee Ronald Reagan traveled yesterday to the farm of his Virginia neighbor, Sen. John W. Warner, to help the state's Republicans launch their fall campaign at a rally that sounded more like a victory celebration than a campaign opening.

Standing on a platform attached to the back porch of Warner's historic stone farmhouse in Fauquier County. Reagan cracked jokes about the Carter administration, but left the serious rhetoric to Virginia Republicans.

"1980" is our year," said Rep. M. Caldwell Butler of Roanoke, who seemed to sum up the attitude of the nearly 4,600 persons who gathered on the hills of Warner's Atoka estate for an event that has become a ritual for the state's powerful GOP. "We are going to take over . . . the Senate, the House and the White House," Butler told the gathering.

Although Butler's predictions about a Republican controlled Congress may be optimistic. Gov. John N. Dalton recalled in another speech that only a decade ago there were no Republicans from Virginia in the House "and this year we have four who are unopposed for reelection."

The hardest hitting speech was delivered by Stan Parris, who is seeking to regain the 8th District congressional seat he lost six years ago to Democrat Herbert Harris in the Watergate backlash.

Paris ridiculed "the so-called get tough policy" of the Carter administration toward Iran. "In the more than 10 months since our diplomats were captured in Tehran and dragged trhough the streets bound and blind-folded, we have admitted 18,027 more Iranian citizens . . . and deported a total of 81," Parris said. He said among the new arrivals are "as many as 2,000 Iranian students with fraudulent and falsified college transcripts."

With the crowd whipped up. Parris asked. "When will this end?" When we get Jimmy Carter out of the White House. When we elect Ronald Reagan. Frank Wolf (the GOP candidate for Congress in the 10th District) and Stan Parris," was his answer.

"Like the man in [the movie] Network, we are mad as hell and we're not taking any more." Parris shouted and the crowd put down their paper plates of barbecued chicken and cheered.

Wolf, trying for the second consecutive time to unseat Rep. Joseph L. Fisher of Arlington, said Fisher "portrays himself as a careful and thoughtful man. But the reality is opposite. He voted with the Carter administration 90 percent of the time.

Reagan came to Atoka from Wexford House a neighboring estate that Gov. John N. Dalton said the governor and his wife Nancy are using "until they move across the river to Washington in January."

The Reagans had planned to spend 45 minutes mingling with the crowd on the rolling grounds. But instead of appearing in sports clothes for a leisurely visit, Reagan showed up in a suit (although he removed the coat) and stayed less than 15 minutes.

But in his brief appearance at the microphone he managed to get off half a dozen jokes about the Carter administration. He apologized for "looking a little like a lawyer from the city," and then quickly added, "I meant no disparagement by that, I don't tell jokes about anyone anymore," a reference to the trouble he got himself into earlier in the campaign with off-the-cuff remarks.

But then the former California governor gave the crowd a sampling of his one-liners:

Example: Carter was supposed to go on '60 Minutes' to talk about his accomplishments, but that left him 59 minutes to fill."

Another: "Carter couldn't get the Russians to move out of Cuba so he's moving out the Cubans."

Also: "Carter's doing his best, and that's out problem."

Finally, Reagan said, he had to "hurry into Washington to make sure they are taking care of the House."

With that, Warner thanked the crowd, which paid $25 a person and devoured 5,250 chickens, for coming to his house and then turned to his wife, actress Elizabeth Taylor, and pointing to the kitchen behind him said, "Tomorrow Liz is going to cook a chicken in this kitchen all by her little old self."

Miss Taylor grabbed the mike and said "That's what he thinks. I will open a tin of beans."

It has been the lure of like Miss Taylor and the proven winning ability of the GOP in Virginia that have made the annual "country supper" a major event. "I'm a Democrat, but don't tell anybody," said Frazier Rhodes, 39, a construction worker from The Plains. "I just came to see Liz Taylor."

For party regulars the turnout was another measure of the confidence they have about carrying Virginia for Reagan this year. It was the only southern state that Carter failed to carry in 1976 and Republicans have had a string of victories in statewide elections since then.

Fairfax Supervisor Tom Davis said that "I haven't seen Republican enthusiasm like this since 1966 when the party recovered from the Goldwater debacle and regained more than 40 seats in the House. I think Reagan will take Northern Virginia and the entire state without much difficulty."

Fairfax Board Chairman John F. Herrity was pleased with the turnout. "Look at all these Republicans," he said, "enthusiasm is there."

Former Virginia U.S. senator William Scott of Farifax said that the country supper has become the premier Virginia political event for Republicans. Anything that will draw this many Republicans together at once has got to be a tradition," he said.

As he mingled with the crowd afterwards, Warner said that he had planned to tell a joke of his own but that Reagan told so many good ones that he held back. But then the senator couldn't resist telling it to a few people with whom he was chatting.

"Do you know the difference between Jimmy Carter and Bill Carter?" he asked. Then grinning broadly, Warner said, "Billy Carter has a foreign policy."