A former Fairfax County woman has been charged by county police with illegally receiving $68,926 in public assistance payments between 1973 and 1980.

The woman, Charlotte Griffin Hall, 27, of the 8000 block of Russell Road, allegedly used five names and reported fictitious children on her applications to obtain various forms of public assistance payments totaling $68,926. Payments were in the form of food stamps, Medicaid, child day care and Aid to Families with Dependent Children, said Fairfax police spokesman Warren Carmichael.

"Whew, that's a lot of money," said George Sheer, supervisor of the state welfare fraud division in the Virginia Department of Welfare, which helps local social service agencies investigate welfare fraud cases. He said he believed it is the largest welfare fraud case in Virginia, the next largest being a 1980 Norfolk fraud case involving $56,000 in public assistance payments.

Hall was charged Wednesday with welfare fraud--a felony punishable by a fine and one to 20 years in jail--during a preliminary hearing in Fairfax County General District Court. The case was bound over to the county grand jury and is tentatively scheduled for trial April 27, said Assistant Fairfax Commonwealth's Attorney Jack Robbins.

Federal prison officials this week turned over Hall, who had been imprisoned in New York state for a previous conviction, to Fairfax County Jail officials. She is being held without bond. Hall's lawyer, Andrew Bury Jr., declined comment.

Hall's case came to the attention of county police when she was convicted in February 1981 on federal mail fraud charges and sentenced to three years in connection with $46,985 in welfare payments she received in Buffalo, N.Y., said Carmichael. Federal prosecutors in New York notified Fairfax officials that Hall had lived in Fairfax and might have illegally sought assistance there.

Acting on the information, police and social service investigators said they found that Hall allegedly had filed public assistance applications with the county under various names, several different Social Security numbers and addresses, and had listed nonexistent children.

Social service officials would not disclose details of how Hall allegedly collected public assistance undetected for so long. They said the $68,926 in welfare payments she allegedly received is more than half the total amount of fraudulent welfare payments county social service investigators brought to court last year.

The number of reported welfare fraud cases has been rising recently in Fairfax--the area's wealthiest county, said Edward C. Amundson, director of eligibility services in the county Department of Social Services. Last year, he said, county prosecutors won 55 welfare fraud convictions involving $130,655 in illegal payments compared with about 40 cases the year before.