The future of a program for emotionally disturbed children in Prince George's County seems secure, thanks to a bill passed overwhelmingly in the closing days of the Maryland General Assembly's annual session. The legislation, sponsored by most of the Prince George's delegation and a handful of other legislators, guarantees the county a full-fledged treatment center by July 1983.

The county's current facility, at Cheltenham in southern Prince George's, was begun in aging buildings six years ago and has served as a model for larger centers in Baltimore and Rockville. Last November, the county Board of Education voted to end educational programs there this summer, after a number of disputes with the Department of Health and Mental Hygiene.

"The most important thing about this whole legislation is that, before, the state has never recognized this as a state-operated facility," said Jo Ann Bell, a member of both the county School Board and Cheltenham's board of directors. Under the legislation, the Department of Health and Mental Hygiene will be responsible for the new center.

Cheltenham combines psychiatric and educational programs. Small classes and individual attention help the 20 resident and 60 day students, who are normal or above normal in intelligence, learn to cope with a classroom environment and, eventually, return to regular public schools.

Parents and teachers at the center, fighting the threat of closure, formed a PTA and organized meetings of officials involved in the dispute. But without funds there seemed to be little hope for a settlement. In February, a boiler blowout forced closure of the main building for three weeks.

In December, Montgomery County delegates protested a state health department plan to reserve 24 beds in the Regional Institute for Adolescents and Children (RICA), in Rockville, for use by emotionally disturbed children from Prince George's.

The legislation passed in Annapolis calls for a committee to make a report by next January, and for a program equivalent to the RICA in Montgomery County to be operating by July 1983.

A 1979 plan for a RICA in Prince George's estimated the cost at $6 million. The most likely site for the new facility, according to school officials, would be one of the county's closed schools.

Until the RICA is established in Prince George's, Bell said, "We have agreed to run the (Cheltenham) facility exactly like it is now."