Daniel Minchew, former aide to Sen. Herman E. Talmadge (D-Ga.) and now his cheif accuser of financial misconduct, pleaded guilty in federal court here yesterday to submitting the government a fake $2,289.99 expense voucher bearing Talmadge's name.

The 39-year-old Minchew, of 3911 Bradley, La., Bethesda, could be sentenced to a maximum of five years in jail and fined $10,000, or both, for his plea to one count of making false statements to the government. No date was set for his sentencing before U.S. District Court Judge John Lewis Smith Jr.

The plea was the result of an agreement that will end Justice Department investigation of Minchew's activities, attorneys said.

However, department sources said their investigation of the senator's finances us still "active". It now focuses on a "special" Talmadge account in Georgia in which Talmadge and several aides have testified they mingled large amounts of personal cash and unspent campaign contributions, investigators said.

Minchew's plea concerned his use of an account opened in his and Talmadge name at Riggs Bank of Washington. One of the deposits involved the $2,289.99 expence check, dated March 26, 1974, which supposedly was a reimbursement to the senator for items such as postage and home office expenses.

Talmadge has denied knowing about the Riggs account, and said he never signed any documents in connection with the account.

Minchew admitted opening the account and signing Talmadge's name to checks drawn on it, but said he did it at Talmadge's direction and most of the cash went to the Talmadge family Justice Department attorneys said.

Justice Department attorney Reid Weingarten of the public integrity section said that about $7,000 of the secret account's funds can be traced directly to Minchew, and that Minchew spent an additional unexplained $11,000 during the period the account was open.

Weingarten told Cheif U.S. District Judge William B. Bryant, who took the guilty plea in Judge Smith's absence, that the government would not specifically ask that Minchew be jailed at the time of sentencing and did not object to his release on personal bond yesterday.

Talmadge has been under investigation for 13 months by the Senate Select Committee on Ethics on allegations of using a secret bank account to divert campaign contributions to his personal use.

The committee has received a formal report from it special counsel calling for sanctions against the Georgia senator.

It will not issue its final report before September, a committee staff assistant has said. He said the panel will meet this week to review the counsel's report, and at least four of the six committee members must approve any recommendation to the Senate of disciplinary action.

The Washington Post repported earlier that Minchew, who now holds a $120,000-a-year consulting job for a group of Japanese businessmen, had a n worth of roughly $1.7 million last year. In addition to government jobs that included an appointments to the International Trade Commission, Minchew hs profited from Capitol Hill real estate.