Anyone can become a monk if a Sanga or an order accepts their request for refuge. Refuge is a spiritual term in Buddhism, meaning give one's life over to the Community, the Buddha, and to surrender.
Becoming a monk does not require residency in China. It would be possible to visit a monastery over a period of time, and to do one's novitiate (time of spiritual preparation) in a Chinese Monastery on a short term visa. Lifetime residency would be extremly difficult to acquire. Ususally, after completing novitiate, a novice monk would be sent to a Sanga or a Community in their own country.