There are at least four millionaires among the candidates for the Senate in Virginia this year, topped by Republican John W. Warner, whose wealth totals more than $7.5 million.

Warner called a press conference here yesterday to discuss his wealth and health (which he says is good), But public financial disclosure reports due Monday under federal law reveal that at least three of the Democratic candidates also are worth more than $1 million.

Clive L. DuVal II, an Arligton lawyer, heads the Democrats with holdings of at least $2.5 million. George Conoly Phillips, the self-styled Christian candidate and Norfold auto dealer, and Frederick A. Babson Jr., a Virginia Beach land developer who is given little chance for the nomination, both show assets of more than $1 million.

The candidates regarded by many as leading contenders for the nominations, Democratic Andrew P. Miller and Republican Richard D. Obenshain, are middle-class lawyers who, while not poor, need the incomes from their law practices to help finance their campaigns, according to supporters.

About half of Warner's wealth is the result of his former marriage to heiress Catherine Mellon. None of the assets disclosed in his report include holdings of his present wife, actress Elzabeth Taylor.

"We decided in the time before we were married to have completely separate interest," Warner told a news conference at which he passed out a statement that spelled out his holdings in greater detail than required by federal law.

"I have no personal knowledge of her holdings," Warner said. "The rule requires you to report only those assets over which you have actual control. It was done (a prenuptial agreement) because of the children. I have three. She has four."

The largest item in Warner's report results from a divorce agreement dated Feb. 4, 1972, that provides an estate currently valued at $3,073,000 for his three children.

Another big chunk of Warner's fortune comes from a life-income trust given him early in that marriage, Jan. 5 1960, his ex-wife's father, philanthropist Paul Mellon. The current value of that trust is $515,000, on which Warner receives an estimated annual interest income of $23,720.

Other major holdings of Warner's include his 2,151-acre Atoka Farm near Middleburge, which is valued by assessors at $1.7 million; his 1,258-acre Milldale Farm in Warren and Clarke countries, valued at $1.1 million, and a house in Georgetown, at 3240 S St. NW, valued at $795,000. Equipment and livestock on the farms added another $360,000 to his worth.

Against assets totaling $7.737 million, Warner listed liabilities of $214,-477 in mortgages and personal loans from the Riggs and Middleburg national banks.

Warner also produced a medical report dated April 21 and prepared by Dr. Julian R. Beckwith, a medical professor at the University of Virginia School of Medicine, in which he was described as "perfectly normal ... 51-year-old man, 191 pounds with his clothes on, heigth 72 inches..."

Because none of the other candidates offered specific dollar values on holdings, calculations from their reports show minimum values, which could greatly understate their wealth. For example, the federal form requires only that values be listed within categories, such as "under $5,000," or "between $15,000 and $50,000" or "$5, to $1,000,000."

Assigning the lowest possible value in each of the reporting categories, other candidates showed these minimum assets:

Democrats: Miller, the former attorney general, $200,000; Phillips, $1.6 million; Babson, $1.3 million; State Sen. Hunter Brooks Andrews, $862,000; Flora M. Crater, $68,000.

Republicans: State Sen. Nathan H. Miller, $260,000; former Gov. Linwood Holton, $160,000; Obenshain, $100,-$200,00.

DuVal, an Arlington lawyer, had the largest and most diverse holdings of any candidate. His largest assets were stock in IBM worth more than $500,000, and in Exxon worth more than $250,000 and his home on Rte. 123 in Fairfax County, valued at more than $500,000.

DuVal also listed several pieces of real estate in Rhode Island, where his wife's father was a textile manufactuer.

Reports of several other candidates were still being processed and were unavailable yesterday.