It is the strongest typhoon to hit Hainan since 2005, said Cai Qinbo, head of the provincial weather station.
According to the official Xinhua News Agency, the country issued its first red alert this year. About 300,000 people evacuated Hainan island where Typhoon Nesat made landfall.
Nesat brought surging waves over Hainan along with fierce winds and severe storms to neighboring Guangxi Zhuang Autonomous Region, sweeping briskly past Hong Kong.
Hainan authorities also canceled flights on the island's airports, closed sea ports, and suspended ferry services and railway transportation. Schools and businesses were also shut down.
Director of the Provincial Water Resources Bureau, Li Hongbo, said the government has given orders to ensure the safety of all reservoirs and to protect people living in both low-lying regions and areas downstream from dangerous reservoirs.
The State Oceanic Administration sent a work team to the island to assist with disaster relief operations.
The typhoon hit the Philippines earlier this week, leaving at least 39 people dead and 31 missing. No deaths or missing people have been reported from China as of Thursday night.
Nesat is expected to arrive in Vietnam tomorrow. --Adelle Platon