With US market at all time high, is it time to lock in profit and shift the funds to China?

Do believe china is the superpower for the next decade but economic conditions dont always translate to stock mkt perf

No.

Personally that was what i did. However do continue to stay investing in the US markets. You can slowly shift funds over to the china markets, but do continue to have a balance between the two. China market is way undervalued, but the US markets has way more optimism ahead.

Warren Buffet's prominent quote “Be Fearful When Others Are Greedy and Greedy When Others Are Fearful”. Highly likely to work in a capitalist economic model.

The China stocks do look attractive now. Would they turn out to be "more" attractive few days or months down the road? It is anyone's guess. If happy with the profits from the US counters, you could either lock it or just sell portion to get back your capital for the next opportunity.

Volatility is part of a long-term investment journey. It will not matter much when you could remain zen regardless of the large swings in your investment.