The growth of essentially Democratic think tanks continued yesterday as former Labor Secretary Ray Marshall announced formation of the National Policy Exchange, an organization unabashedly critical of the Reagan economic program.

The center, which has strong ties to organized labor, expects to get an annual budget of about $500,000 to finance papers on economic issues. At a press conference yesterday, two prominent economists who will act as chairmen of the policy studies advisory board indicated that income policy--an issue the Reagan administration has chosen not to address--will be one focus of the organization.

"The main achievement of the administration so far . . . has been a shift of wealth to the wealthy and power to the powerful," Robert Solow, professor of economics at the Massachusetts Institute of Technology, said. The other cochair is James Tobin, a Yale economics professor and 1981 Nobel laureate.

Since the 1980 election and the major setback suffered by Democrats, there has been a flowering of Democratic think tanks in an effort to develop policies and strategies to counter the intellectual vitality that has characterized the GOP in recent years.

Among the other prominent new organizations are the Center for National Policy, a centrist group that recently changed its name to the Center for Democratic Policy, and the Democracy Project, a more liberal organization.

The National Policy Exchange was started with seed money from organized labor, but Marshall said he intends to try to have the sources of money split evenly among unions, corporations, individuals and foundations.

He described the center as nonpartisan, but the board is overwhelmingly dominated by Democrats, including Sen. Edward M. Kennedy (D-Mass.) and former vice president Walter F. Mondale. The one prominent Republican on the board is former Massachusetts senator Edward Brooke.

In a preliminary paper by Tobin and Solow, the two economists argued that the administration's failure to have an incomes policy and a strategy to control the steep inflation in such sectors as medical care will make the resolution of the stagflation problem extremely difficult to achieve.

"Fiscal and monetary policy can produce no magical surgical strike that cuts out inflation, without first hitting the real economy of production, jobs and profits. To avoid that costly process, we will have to experiment with less conventional policies. Some of these fall under the heading 'incomes policies' and some require programs to correct structural defects in such sectors as medical care, housing and transportation," they said.

One of the main differences between the National Policy Exchange and the Center for National Policy is that the exchange will focus on domestic, economic questions, while the center will also produce papers on foreign policy and defense spending.