Adjusting to a 30 percent cut in its budget, the Consumer Product Safety Commission agreed yesterday to reduce its staff drastically by nearly 200 employes and to eliminate half of its 10 regional offices.

At the same time, however the commission unanimously accepted a proposal of its new chairman to decentralize many of the agency's activities to give the remaining regional offices a greater say in investigations into unsafe products.

In so doing, the commission agreed to abolish its communications office of 43 workers, directing the field offices to assume a larger role than Washington in disseminating product safety information to consumers.

The unanimous vote came after a long and tedious commission meeting in which the five members discussed ways to reorganize the agency to make it as efficient as possible, given the sharp reduction in its budget.

It was the first meeting conducted by the new chairman, Nancy Harvey Steorts, and controversy was carefully avoided when the commission decided to delete from its reorganization plan six operating principles suggested by Steorts. The principles stressed that the commission will place its emphasis on working with industry groups to develop voluntary standards and consumer education programs. At least three commissioners objected to the principles, however, because they failed to note that the agency still would impose mandatory rules -- or even ban products -- when voluntary efforts failed.

Under President Reagan's campaign to trim the federal budget, the small consumer agency's proposed $42.1 million budget for the fiscal year beginning Oct. 1 was trimmed to a little less than $33 million.

Before Steorts assumed office last month, the commission agreed to meet the bulk of this cut by reducing the number of field offices from 10 to five. However, the commission decided to leave intact most of its substantive investigations into such products as chain saws, house wiring, upholstered furniture, and goods made with formaldehyde and asbestos.

Upon taking office, Steorts asked the commission to hold off implementing the plan until she had time to review it and make her own suggestions. It was those suggestions that were discussed and approved yesterday.

Steorts did not propose changing the agency's programs but rather changing its structure.

Although the changes do not affect the direction of the agency, Steorts said afterwards that the reorganization is signficant because it "streamlines the way we do business, which will affect the substance because it will mean more involvement by the consumer in what we do."