The District of Columbia Board of Elections and Ethics ruled yesterday that City Council member Nadine P. Winter (D-Ward 6) violated a campaign law last year by using city employes and office facilities in her reelection campaign.

Winter faces a possible reprimand or fine, probably following a hearing. Board they consider the violations serious.

The findings by a 2-to-0 vote was believed to be the first instance of an elected city official determined to be violating the city's campaign law.

Winter filed a statement with the Office of Campaign Finance, the semi-autonomous arm of the board that investigated the charges, in which she neither contested nor admitted violations. She insisted to reporters that she was innocent, and had agreed to accept board action because "it has been dragging on for months, and I am tired of it."

The board acted on a complaint filed last fall by Rebecca Francis, who formerly worked in Winter's council office and later on a council committee staff, on a federally financed CETA job.

When the CETA job expired last October, Francis publicly endorsed Winter's unsuccessful rival in a write-in campaign, Patricia Rice Press. In a statement at the time, Francis charged that Winter had assigned campaign tasks to employes paid by the city and federal governments.

At the time, Winter described Francis as "a disgruntled employe." She repeated that description yesterday.

The elections board did not release the Office of Campaign Finance's detailed investigative report of the case. After only brief discussion yesterday, it adopted a seven-point "opinion and order" drafted by Lindell Tinsley, the campaign office's deputy director, that provided scant detail of the findings.

The opinion exonerated Winter from any illegality in distributing a newsletter in February and March 1978 on council stationery, saying this was "within the scope of her official duty."

It found these violations:

Winter "along with campaign workers, representatives or designated agents, utilized council space and office supplies to promote certain campaign activities."

Winter "used the services of council staff and CETA employes to assist in campaign-related activities."

The board document said thatFrancis, Winter's accuser, "did not substantially participate" in the council member's campaign.

Francis called the finding a "white-wash," and said she would take the case to the U.S. Atorney's office. When Francis made such a comment yesterday to Jeanus B. Parks, the elections board's acting chairman, Parks accused her of tyring to intimidate the board. She denied it.

James L. Denson, currently the board's only other member, said the board itself may set the amount of a possible fine to be levied against Winter. He said the law does not specify limits.

In a related development, a D.C. Department of Labor hearing officer ruled that Francis should be given a satisfactory rating for job performance when she worked in Winter's office, erasing a lower rating. CAPTION: Picture, NADINE WINTER . . . "I am tired of it"