The Democratic Policy Commission completed a harmonious two-day session here today, listening to its leaders call for the party to rid itself of "the paralysis of the Vietnam syndrome" abroad and to adopt an industrial policy at home built around federally funded regional research-and-development centers.

The panel also heard proposals for more federal funding for day care, Head Start, college loans and other programs for families with children.

The year-old commission, chaired by former Utah governor Scott M. Matheson, is made up of 100 elected officials, most of them at the state and local level. Next month, it will present to the Democratic National Committee a final report intended to serve not as formal party platform but as a statement of values and policy goals.

In a foreign policy speech to the panel today, Sen. Joseph R. Biden Jr. (D-Del.) called on his party to find a "common-sense" middle ground between "the ideological demons of both the right and the left."

"The right is mobilized by simplicity, but the left is immobilized by complexity," Biden said. "There are people in our own party . . . who see a potential Vietnam in every hot spot in the Third World, and their doctrinaire prescription is that the consequences of action are always more undesirable than the consequences of inaction."

Biden said the test of whether the United States should resort to the use of force should be based not on ideology, but on two questions: "Is it right, and will it work?"

Sen. Sam Nunn (D-Ga.), ranking minority member on the Armed Services Committee, said the increase in terrorism has made funding for U.S. intelligence activities a top priority. Rep. Dave McCurdy (D-Okla.), called on Democrats to support continued adherence to the unratified SALT II treaty and to back the mobile, lightweight, single-warhead Minuteman missile as a solution to the vulnerability of land-based nuclear weapons.

On the domestic front, Gov. Michael S. Dukakis of Massachusetts called for the federal government to put up seed money to create 15 to 20 regional Centers of Technological Excellence, where local industry, academic and research institutions could develop ways to improve regional economies. He also urged creation of federal Economic Development Block Grants that would be targeted to economically distressed regions.

In addition, Dukakis called on Democrats to make an issue of tax evasion, saying the federal government should follow the example of Massachusetts and other states and crack down on tax cheats.