Chinese diplomats here and around the world passed word yesterday that Vietnam has been "taught the lesson" and therefore People's Republic of China military forces soon will be able to withdraw.

No timetable for a Chinese pullout from Vietnam was reported, and American officials said U.S. intelligence agencies had no information that a withdrawal has begun.

Washington officials took the well-coordinated Chinese diplomatic campaign as a hopeful sign of an approaching end to the two-week-old invasion of Vietnam, which Peking from the start described as limited in scope and duration.

Peking's talk of peace, however, was as subtle and ambiguous as its military tactics in the strange war of shadow and maneuver.

In Washington, for example, Ambassador Chai Tse-min at his request called on Secretary of State Cyrus R. Vance at the State Department yesterday afternoon. After an hour-long meeting, Chai told reporters that he has "no formal informationc from his government but that in his "personal opinion" the Vietnamese have been "taught the lesson" and that China therefore can withdraw.

News reports from Peking and Tokyo quoted Chinese officials there as saying a decision has been made to withdraw. A similar message is reported to have been passed in Bangkok, Belgrade and a number of other capitals.

China officially described its Feb. 17 invasion as a "counterattack" in response to Vietnamese border encroachments. However, senior Peking officials said before and since the attack that the purpose is to "teach a lesson" to Vietnam that it cannot act with force in unrestrained fashion.

One theory prevalent among American officials was that China was invoking the "Aiken formula" of disengagement named for then-Sen. George Aiken (R-Vt.). During the early stages of American combat involvement in Vietnam, Aiken recommended that the United States simply declare a victory and then withdraw.

The desire for a credible claim of some success, as a rationale for withdrawal, was seen by some officials as the explanation for Chinese attacks on the provincial capital of Langson. U.S. officials said their reports indicated China controls the city, while Vietnamese forces in the mountains around it can shell the city with ease. Chinese troops are said to have moved into Langson late last week, though they could have done so -- at a cost in lives -- at almost any time since their invasion began.

The Chinese "peace campaign," officials pointed out, has the effect of easing the worldwide criticism and apprehension, even while military action continues. Due to the lack of a clear timetable for the withdrawal, it remains possible that the war could continue or even grow in intensity for a while depending on battlefield decisions on both sides.

In recent days U.S. intelligence reports have progressively increased the government's estimate of the number of Chinese troops and aircraft deployed either inside Vietnam or in the border region to the rear of the battle zone. Latest reports indicate that 300,000 to 400,000 Chines troops are involved, along with close to 1,100 transport, reconnaissance or combat aircraft.

Despite the presence of this very large Chinese army and, on the other side, a formidable force of well-trained and well-equipped Vietnamese, so far there have been no major ground battles, and not a single reported air engagement.

The Chinese forces have stayed in the rugged hills that mark the border, and the Vietnamese main infantry divisions have stayed in the lowlands near Hanoi. The attacks and skirmishes, rarely if ever involving more than a regiment (a little more than 2,000 men), have taken place between Chinese troops and Vietnamese border forces and militia, according to U.S. analysts.

The sketchy information available from satellite photography and interception of battlefield communications suggests that the two sides have been feeling each other out, largely in night operations, more in an effort to inflict damage rather than to occupy land or cities.

While thousands of soldiers are reported to have been killed, either by mortar or artillery or hand-to-hand combat, the war so far has been more an Oriental wrestling bout of circling and testing than a classic military confrontation in the western tradition.

Despite recurrent rumors and suggestions to the contrary, officials said there still is no sign of Soviet mobilization or other preparations for military action in retaliation against China for punishing Vietnam, Moscow's ally. After a careful reading, analysts interpreted Friday's Soviet government statement warning China to withdraw as an effort to marshal world opinion against China rather than an expanded threat of retaliation.