Donald P. Hodel, a former energy consultant who has served since the start of the Reagan administration as interior undersecretary, has been chosen by President Reagan to succeed James B. Edwards as secretary of energy, White House sources said yesterday.

Edwards, a South Carolina oral surgeon who failed in his goal of becoming the "first Cabinet member in the history of the United States" to abolish his department, plans to resign after next week's elections to become president of the Medical University of South Carolina.

W. Kenneth Davis, a former Bechtel Corp. executive who served under Edwards as deputy secretary of energy, also is expected to resign after the election, and sources said Irene Wischer, a Texas oil executive, is being considered for the No. 2 position in the department.

Neither Hodel nor Wischer returned telephone calls yesterday, and Hodel's wife, Barbara, reached at their home in Arlington, said she was not aware that her husband had been notified formally by the White House of the appointment.

"A little certainty would be nice," she said. "We've been on tenterhooks for a long time."

Davis, reached at home last night, declined to discuss his plans.

Hodel, 47, was administrator of the Bonneville Power Administration from 1972 to 1977 before founding his own firm, Hodel Associates Inc., which did consulting work for a number of major western utility companies. He also served from 1978 to 1980 as president of the National Electric Reliability Council, a nonprofit organization of publicly and privately held utilities.

Hodel is known at the Interior Department as a quiet, behind-the-scenes manager, who presents a dramatic contrast in style to his boss, Secretary James G. Watt.

But Hodel, according to several interior officials, embraces most of Watt's conservative ideology, favoring a speedup of natural resource development on public lands and an easing of present restrictions that protect those lands from exploitation.

Hodel's job has been to push Watt's policies through the Interior bureaucracy, and he is given much credit within the agency for the changes Watt has brought in "shifting the pendulum" toward a policy of relaxing restrictions on development of public lands.

"After the ideologues come in and ruffle the feathers, Hodel comes in and gets things under way. That's why he's viewed almost as a voice for moderation, when in fact he doesn't differ much at all from Watt ideologically," said an official who worked with both men.

Wischer is president and chief executive officer of Panhandle Producing Co. of San Antonio, an oil and gas company founded by her late first husband.

A member of the board of the San Antonio Chamber of Commerce, she is well known in independent oil circles and has been involved in Texas Republican politics since the 1960s. She was active in the presidential campaigns of Barry Goldwater and Richard M. Nixon.

Sources said the only impediment to her appointment was that she might have difficulty divesting her energy holdings.

While Hodel had long been rumored to be a leading candidate to succeed Edwards, who announced his intention to resign last spring, Davis' decision to leave had been a better-kept secret.

During the summer, in fact, Davis had been viewed widely as the most likely successor to Edwards.

That possibility, however, declined sharply after the president named George P. Shultz as secretary of state. Both Shultz and Defense Secretary Caspar W. Weinberger are former top officials of Bechtel, a large San Francisco-based engineering company. Few thought that Reagan would name a third former Bechtel executive to a Cabinet post.