Prince George's County Executive Lawrence J. Hogan tonight moved decisively into President Reagan's corner on the important issue of the economy as he campaigned in his bid for the Republican nomination for the U.S. Senate in Maryland.

At a fund-raiser in a historic Charles County mansion near here, Hogan embraced Reagan's "overall approach" to the economy as "the right course" for the nation. In turn, Hogan won his first endorsement from a member of the president's cabinet, Energy Secretary James B. Edwards.

Edwards praised Hogan for his "sound political philosophy" and his record in government, and told the crowd of about 125 Hogan supporters, "we need more like him in the U. S. Senate."

Hogan said that although he "parts ways" with Reagan on a number of issues, "I am confident things are going to turn out all right if we follow the course he's directing us on."

Hogan, who would like to replace liberal Democrat Paul Sarbanes in the Senate, also said the campaign will be about more than "Reaganomics. Paul Sarbanes might prefer to run against Ronald Reagan, but he'll have to run against Larry Hogan, and I have a knack of beating Democrats," said Hogan, who has beaten Democrats for Congress and county executive in overwhelmingly Democratic Prince George's County.

In the Republican Senate primary on Sept. 14 he faces political newcomer V. Dallas Merrell, a conservative businessman in Silver Spring.

Tonight's fund-raiser was held at Rose Hill mansion, home of Charles and Constance Stuart, who were White House staffers during the Nixon administration.