Maryland prison officials today presented to the leadership of the General Assembly a $50 million plan to renovate the dilapidated and troubled Maryland Penitentiary, the state's maximum security prison in Baltimore.

The plan, which includes demolition of three aging buildings and construction of a 300-cell "super maximum" security prison next to the penitentiary for the system's most disruptive prisoners, apparently satisfies some of the concerns of legislators who have threatened to deny the corrections department part of its operating budget unless substantial improvements are made.

Patterned after two similar renovation projects under way at prisons in Kansas, the major refurbishing of the facility that dates to the 19th century would transform the penitentiary into "a very different kind of institution," than it is now, promised Frank A. Hall, state Public Safety and Correctional Services secretary.

Legislative leaders who were briefed on the proposal by Hall and corrections commissioner Arnold J. Hopkins warned that upgrading the penitentiary was only a partial answer to the system's endemic problems of overcrowding and inmate idleness.

"The plan is one that appears to solve the penitentiary problem, but it does not address the potential overcrowding we face," said House Appropriations Committee Chairman R. Clayton Mitchell, Jr. (D-Kent).

Prison officials are to present to the legislature sometime next week a five-year master plan for coping with an anticipated increase in prisoners that they expect will require construction of another 1,500-bed prison by 1992. There are currently about 12,700 prisoners in the system, which is designed for about 9,300.

The state is building a new prison for 2,000 inmates in Somerset County, but the prison population is expected to grow to between 14,000 and 15,000 by 1992.

House Speaker Benjamin L. Cardin (D-Baltimore), who has been increasingly critical of the state's prison administrators since the October slaying of a guard at the penitentiary, said the plan presented today "will convert the penitentiary into a usable facility."

But Cardin and other legislators indicated they still have some objections to a major element of the plan, the $22 million building that would house maximum security inmates now confined in the penitentiary's south wing.

That is the unit where guard Herman Toulson Jr. was killed in October and which the attorney general in a subsequent investigation called the "innermost circle of hell" in the prison system.

Some legislators believe Baltimore may not be the most appropriate site for a maximum security facility. Lawmakers are also expected to negotiate with the Hughes administration over where to find so-called "surge space" needed to house prisoners while the penitentiary is being renovated. One plan being discussed is to have local jails house some short-term and non-violent prisoners.

Other components of the renovation plan, the bulk of which would be completed sometime in 1988, include:

* Substantial structural and mechanical improvements to the penitentiary's south and west wings that house most of the institution's prisoners, at a cost of about $8 million. The five-tier cell blocks in those wings would be divided by construction of a new floor. Narrow catwalks along each tier, now about three feet wide, would be more than doubled to improve security for both guards and inmates. Also, plumbing, electrical and water systems would be replaced.

* Demolition of three antiquated buildings on the complex. Among those three are a dormitory now housing 200 prisoners which dates to 1864, and a former woodworking shop where about 100 prisoners are confined. Both would be torn down. Removal of the buildings would substantially increase recreation space.

* Construction of a $3 million building to house vocational training and recreation facilities, including a gymnasium.

The effect of the renovations, said Hall, would be to "give us a very workable, safe institution." Once the project is completed, the penitentiary complex, which sprawls over 5 1/2 acres in downtown Baltimore, would house about 200 prisoners fewer than the 1,300 currently incarcerated there.