Lame duck Sen. Edward W. Brooke (R-Mass.) will face an attachment on $300,000 of his campaign funds unless he can prove that he will be able to pay taxes on his former wife's St. Martin's home - part of the award in their divorce settlement last summer.

Ruling on a motion by Remigia Brooke, Middlesex Probate Judge Lawrence T. Perera ordered the senator to present evidence to the court by Wednesday that he will be able to meet the payment by Dec. 1.

That date was requested by Brooke as an extension of his deadline for paying the transfer and capital gains taxes, estimated at between $50,000 and $115,000.

According to an earlier agreement, the senator was to have made the payment yesterday, finally ending the acrimonious divorce case that many political observers say was the primary reason for Brooke's reelection defeat Nov. 7 by two-term Rep. Paul E. Tsongas.

The court, meanwhile, is holding a deed to Brooke's Martha's Vineyard property as insurance against default on payment of the taxes on the Caribbean island property.

Mrs. Brooke's attorney, Paul Perocchi, said he requested a $300,000 attachment because, if Brooke were to convert excess campaign funds to his own use, after taxes there would be only $90,000. Combined with $25,000 in equity on the senator's Martha's Vineyard home, the total would be $115,000, the figure given as the highest possible tax bill.

However, the senator's press secretary, Robert Waite, said yesterday the campaign committee is currently $50,000 in debt.