Treasury Secretary W. Michael Blumenthal hinted to a blue-chip Wall Street audience today that Carter administration will not recommend elimination of the capital gains preference in any tax legislation it submits to Congress next year.

The forthcoming proposal will contain incentives for capital information, both for corporations and individuals, Blumenthal told the investment chiefs in a speech filled with the kind of things Wall Street like to hear.

Then he backpeddled from the controversial proposal to eliminate preferred tax treatment for capital gains - profits from the sale of stocks or other assets - that the administration until recently had floated as a key part of its tax overhaul package, but which has drawn considerable resistance from the investment and business community

"We fully understand the important role that preferential tax rates for capital gains have played in encouraging capital formation - especially for venture capital and new businesses," Blumenthal said. "We will, of course, take this into account in designing reforms to reduce or eliminate unjustified tax preferences.

And later he told reporters that the tax program - which should be completed in the next week for submission to President Carter - will be relatively simple, a further indication that the elimination of capitals gains won't be included.

Half of capital are sheltered from taxation if assets are held for a minimum period. And elimination of this preference to make more palatable was to have been joined with proposals to do away with the double taxation of corporate dividends and a reduction in the minimum tax rate on individuals.

However, along with elimination of the preferential rates drawing fire from Wall Street, where the special treatment of capital gains is considered a key incentive for individuals to invest in stock market, influential members of the Congress like House Ways and Means Committee chairman Al Ullman (D-Ore) also have warned that a tax complex program aimed at reform of the tax system should be avoided in an election year, with the emphasis instead on individual and business tax cuts.

In his sold-out speech to the Bond Club, Blumenthal also said the administration will soon unveil in full detail "a cogent, comprehensive economic strategy for the next three years with emphasis above all . . . on the private sector, on the market mechanism, and on the reliance on the genius of the free market system."

He also addressed the investment community's most immediate woes - a slumping stock market and a drought of new equity underwriting - problems which he said were serious and merit the immediate attention of this administration.

But Blumenthal then said the solution to the depressed condition fo the stock market lies not with specific government actions but with an improved U.S. economy that in turn depends primarily on decisions by businessmen to expand.

"The problem will begin to be solved only when business executives singly and collectively, decide that the best course toward profitability is (See BLUMENTHAL, D14, Col.1> through expansion," the Treasury Secretary said.

"That's a basis reality," Blumenthal told the audience, and "that's why we will rely on a steady, prudent set of policies for lasting economic results, fully aware that the really big problem take time to solve."

The Treasury Secretary appeared to have one specific piece of good news - that the Securities and Exchange Commission probably will wait to eliminate New York Stock Exchange Rule 390 and other rules prohibiting off-board trading by brokerage firms until the components of a national market system are in place, which could be some years away.

The Treasury Secretary's speech seemed clearly aimed at drumming up Wall Street confidence in the Carter administration by emphasizing concern about the stock market - which has dropped by 200 points since the beginning of the year when the President took office - and by proclaiming a philosophic commitment to the private sector.