President Carter yesterday invited 25 mayors from some of the nation's most financially strapped cities to watch him sign the $20.1 billion bill that will fund his jobs and economic stimulus program over the next two years.

AFL-CIO President George Meany, who has charged Carter with failing to keep his promises to working people, attended the signing ceremony in the White House Rose Garden.

Some of the mayors went from the White House to an economic policy meeting, where they said, in effect, that the stimulus program is a nice first step but that Carter will have to do much more before their problems can be eased.

The bill Carter signed is a mixture of a little old money appropriated under President Ford and a lot of new money to be spend in creating an estimated 1.3 million new jobs through the rest of fiscal 1977, which ends Sept. 30, and all of fiscal 1978.

Its main features:

$7.9 billion for public service jobs. Some $1.3 billion of that was authorized last year, and the program currently provides 310,000 jobs in a variety of local government agencies, including police, fire and health departments.

Labor Secretary Ray Marshall ordered all but $100 million of the remaining $6.6 billion released immediately to create 415,000 new public service jobs under the Comprehensive Employment and Training Act (CETA).

The bill funds the new total of 725,000 jobs through fiscal 1978. Some $1.14 billion will be sent to areas of high unemployment, and the rest will be allocated as local governments see fit.

$4 billion for public works projects. Last year President Ford authorized $2 billion for such projects, and the Commerce Department was flooded with 25,000 applications seeking $25 billion worth of projects.

Carter then asked for $2 billion more for fiscal 1977, and another $2 billion for fiscal 1978.

Congress gave him the $4 billion but said almost all of it has to be spent by Sept. 30. A Commerce Department spokesman said the first grants will probably be announced in early summer. The money, targeted to areas hardest hit by unemployment, can be used to build libraries, municipal buildings, schools, sewage treatment plants and other local capital projects.

About $630 million for the remainder of this fical year for the existing "countercyclical" revenue-sharing program, which pays extra money to states and local governments whenever unemployment tops 6 per cent.

4.99 billion for the regular revenue-sharing program for the rest of fiscal 1977.

Carter told his audience, "We've still got a long way to go" to revive the economy.

He said the $4 billion in public works money will create an estimated 600,000 new jobs in construction and related industries.

Each state will get at least $30 million of the $4 billion, he said. Two per cent of the total will be set aside for Indians and Alaskan natives, and 10 per cent will be spent through minority businesses.

The $7.9 billion for public service jobs includes some 200,000 jobs set-aside for youth.

Less than two hours after Carter signed the bill, the economic policy committee of the U.S. Conference of Mayors passed a resolution urging him to "enlarge the budget stimulus for direct job-creating programs" in view of "the disappointing economic recovery."

The resolution also asked for more countercyclical aid. A second resolution, which the committee also adopted, urged the President and Congress to create an urban development bank that would spend federal money to help businesses in declining areas.

The Treasury Department is looking into that possibility as part of a three-month study of urban finance options. CAPTION: Picture, Juanita Kreps, Sen. Jennings Randolph and New York Mayor Abe Beame - along with other mayors, legislators and senators - applaud President Carter as he signs the $20.1 billion bill to fund his economic stimulus program over the next two years. . By Craig Herndon - The Washington Post