C. Todd Conover, the controversial comptroller of the Currency, announced yesterday he plans to resign this spring. No successor has been named.

Conover, 44, said he plans to return to the private sector because he has accomplished most of what he wanted to do in deregulating financial services. At a press briefing he made clear his frustration with Congress for its failure to pass legislation taking deregulation further, although he denied that was the reason for his departure. He also noted that the opportunities for his agency to take its own deregulatory actions were decreasing.

During the past three years, his independent pursuit of deregulation, including the approval of 130 nonbank banks, and his handling of the Continental Illinois National Bank and Penn Square National Bank fiascos have won him mixed reviews from government and industry.

"Todd has done a very good job in probably the most difficult circumstances since the 1930s," Sen. Jake Garn (R-Utah), chairman of the Senate Banking Committee and a champion of deregulation, said yesterday. R. T. McNamar, deputy secretary of the Treasury, called him "as effective a comptroller as we've ever had."

On the other hand, Rep. Fernand J. St Germain (D-R.I.), the House Banking Committee chairman who has clashed with Conover over his policies, noting "my concern that Conover's aggressive stance in favor of the banking community's expansionist plans runs counter to the intent of Congress and the wishes of the public," said he hopes the president will "choose his successor wisely."

There were opposing views within industry as well. James G. Cairns, president of the American Bankers Association, praised Conover, saying, "While often criticized, he has consistently enunciated the customer benefits which can be expected when financial institutions are allowed to offer additional services." But Kenneth Guenther, executive director of the Independent Bankers Association of America, which opposes some aspects of deregulation, said he hopes Conover's successor will be "a person more sensitive to the needs of all segments of the banking industry at these crucial times."

Conover said yesterday that he does not expect that the views of the newly nominated secretary of the Treasury, former White House chief of staff James A. Baker, will be significantly different from those of Treasury Secretary Donald T. Regan. Regan will assume Baker's former duties in the White House. The Treasury secretary is the comptroller's boss.

Ben Love, chairman of Texas Commerce Bankshares Inc. of Houston, a longtime colleague of Baker, said one of Baker's advantages is that he understands not only the East (from his days at Princeton), but also the regional perspective (from his Houston experience). That could be construed as a difference with Regan, who as former chairman of Merrill Lynch, is often thought of as partial to the East and big business. Regional banks have been at odds with the big money-center banks about what path deregulation should follow.

Conover, who supervises the 4,700 federally chartered commercial banks, said he hopes he will be remembered as a promoter of deregulation, a firm supervisor and a good office manager rather than as one who approved nonbank banks, the focus of criticism over Continental Illinois and Penn Square, and the one who presided over the most bank failures since the Depression.