Typhoon Kalmaegi has made landfall in China's southern Hainan province, after barrelling past the Philippines and Hong Kong.
Tens of thousands were evacuated ahead of the typhoon's arrival around 09:40 local time (01:40 GMT), said Xinhua.
Schools were closed in Haikou city and dozens of flights were cancelled.
The typhoon had earlier caused strong winds to pound Hong Kong, where at least 29 people were injured, said the AFP news agency.
More than 500 flights were delayed and morning trading on the Hong Kong stock exchange was cancelled.
The storm blew in from the Philippines, where it cut power and soaked farmland.
At least six people are reported to have died when a ferry sank in the central Philippines on Saturday evening, after stalling in bad weather.
In Manila, a ferry capsized in rough seas but all 15 crew members were rescued. But Philippine officials said the storm largely avoided heavily populated areas.
In Hong Kong, a level eight cyclone warning was in place on Monday evening, on a 10-point scale. Schools and businesses were ordered to close until the storm warning was lowered.
Before midday on Tuesday the warning was down to three, however, as the storm headed to Hainan.
"Although Kalmaegi is moving away, occasional gales will still affect the south-western part and high ground of Hong Kong," the Hong Kong Observatory said.
In China, dozens of flights were cancelled as the typhoon approached, including all flights out of Haikou, the capital of Hainan province, Xinhua news agency said.