First Lady Rosalynn Carter yesterday criticized the physical appearance of D.C. General Hospital and promised to work to help improve it.

"I was told, quite frankly, that if a patient didn't feel ill when he went to the hospital, he would after he saw the physically unattractive public areas," the first lady said in a speech at the dedication of a water sculputure at the Orlando, Fla., Federal Building.

Mrs. Carter, who said two weeks ago that she would become involved in projects aimed at improving the quality of life of inner city residents in Washington and other cities, said yesterday she plans to visit D.C. General this week.

The first lady said members of the hospital's new governing board described it to her as a place of "ugly rooms without any signs of beauty . . . battleship gray halls . . . barren waiting rooms that plunge both patient and family into depression . . . a working environment that is demeaning to the medical professionals."

Gilbert Hahn, former D.C. City Council chairman and now chairman of the board that look over control of the hospital last fall, said he is "very pleased by Mrs. Carter's interest."

Hahn said he, hospital executive director Robert Johnson and board member Natalie Spingah met with Mrs. Carter at the White House last Wednesday. They discussed problems of the trouble-plagued institution, which serves only the poorest of the city's residents.

"I think one of the things on the list that much have caught her eye or ear was this idea that you ought to be able to deliver care to people, even in a public hospital, without its being too dreary."

In addition to being a physically depressing place, D.C. General has been unaccredited since December 1975, when the Joint Commission on the Accreditation of Hospitals found 14 major violations of hospital standards at the institution.

Those violations involved staffing patterns, improper and inadequate record keeping and physical safety code violations. The hospital was reinspected in May 1976 and neither the results of the reinspection, nor subsequent appeals, won it reaccreditation. The hospital currently is in danger of losing its HEW accreditation and the right to receive Medicare payments.

In her speech, Mrs. Carter said she wants to "help brighten our city's hospital by calling for creative plans from our community to brighten up this important public institution. I know what a difference we can make with a little paint, with good art, with interesting arrangements," she said.

Spingarn, the hospital board member who apparently aroused the first lady's interest in the institution by writing to her about its problems, said yesterday she is "extremely pleased" by Mrs. Carter's remarks.

The backing of the first lady, she said, is "a magic wand" for the hospital.