Treasury Secretary W. Michael Blumenthal is scheduled to leave Washington this morning for Peking, to begin talks with Chinese leaders that could lead to greatly expanded Chinese-American trade and economic ties.

Blumenthal, the highest ranking official to go to the Peoples Republic since "normalization" of relations on Jan. 1, will be President Carter's representative at the formal reopening of the U.S. Embassy in Peking on March 1.

Officials considered, then abandoned after a last-minute debate, the possibility of postponing the Blumenthal trip to indicate U.S. uneasiness over the Chinese military invasion of Vietnam. Officials are trying to keep hands off the Sino-Vietnam conflict, and hope the fighting will end with-out pulling the Soviet Union -- a Vietnam ally -- into the fray.

Blumenthal will be carrying a message from President Carter to the Chinese leaders on the subject of the "Chinese-Vietnamese situation", officials said yesterday. They refused to answer questions on the substance of the Carter message.

The administration sees the potential for a vast new market for American business in China that would in future years result in substantial exports for U.S. companies, helping to offset large trade deficits with other countries, especially for oil.

U.S. officials recognize that many obstacles to expanded trade have arisen over the years, and the process of renewing relationships on all fronts may be slow. It was learned that on instructions from the White House, Blumenthal is prepared to discuss with Vice Premier Teng Hsiao-ping the establishment of a Joint Economic Commission to see if "impediments" to broad relationships can be systematically removed.

Blumenthal, accompanied by key State Department, Commerce Department, and Treasury aides, will have formal talks with Vice Premier Teng and other Chinese officials for a week in Peking, then spend two days in Shanghai, where he lived as a youth during the Japanese occupation until 1947.

He will make a brief stop in Tokyo enroute home for his first meeting with the new Japanese Prime Minister, Masayoshi Ohira. Blumenthal is expected to impress on Ohira the need for Japan to take some highly visible steps to curb its growing trade and current account trade and services surpluses.

Carter administration officials have been cautioning against expecting quick or dramatic results from the Blumenthal mission. The first item on the agenda will be an attempt to resolve outstanding and conflicting monetary claims that each country has against the other.

This, and other substantive issues, including a bilateral trade treaty, China's access to "most favored nation" status (which she is now denied), and, ultimately, the ability to borrow money from public and private lenders in the United States, will be opened for the first time.

The problem of the claims-assets issue centers on the fact that Chinese claims in the U.S. amount at most to only $76.5 million, while U.S. claims against China are much more -- $196.9 million.

But somehow, Blumenthal and Teng will have to set a process in motion that will wipe the slate clean, and be acceptable to Congress. Until that is done, any American claimant could attach Chinese property here -- say, a commercial vessel or goods on exhibit at a trade fair.

China does not recognize the legitimacy of the U.S. claims, all going back to the pre-1949 period. But in the discussions here earlier this month between Teng and Carter, it appeared that the Chinese were anxious for a solution of the problem A PRC government contribution toward settlement of the claims-assets question is not ruled out by American officials.

The next order of business for Blumenthal will be discussion of a bilateral trade treaty, which is a necessary preliminary step to consideration of MFN status for China. The Chinese are anxious for the lower tariff treatment that "most favored" nations get, to help earn the foreign exchange needed for its ambitious modernization goals.

That will require, somewhere along the line, a Chinese emigration policy that would allow it to qualify for MFN status under the Jackson-Vanik Act. It requires socialist countries to demonstrate that they have a liberal emigration policy.

There are some other impediments to the free flow of trade. China clearly would like access to Export-Import Bank loans -- but at the moment, there is an outstanding debt of about $23 million (plus more than that in interest) going back to the days of Chiang Kai-shek. There is some thought among American officials that the old Ex-Im loans might be forgiven, along with a much smaller debt of $660,000 to the U.S. Postal Service.

All of this, of course, would be preliminary to boosting the U.S.-China two-way trade, at a mere $1 billion in 1978, to something much more than that. Cautiously, officials speak of the two-way trade running to $2 billion this year, and then considerably more if China can find ways to finance all of its requirements.