Doksuri moved off the Philippines on Thursday morning and was headed across the Taiwan Strait to southeastern China with maximum winds of 191km/h, the weather bureau said.
It is expected to make landfall over Fujian province on Friday.
The Philippines national disaster agency said five people were killed in floods and landslides, while police and local authorities tallied two more fatalities.
A total of 328,356 people in 31 provinces were affected by Doksuri, including 26,697 residents forced to flee their homes, the agency said.
The typhoon lashed the northern Philippine coastline on Wednesday, bursting banks of rivers, flooding low-lying villages and unleashing dozens of landslides.
Doksuri knocked out power in most of the affected provinces, while dozens of flights were cancelled and sea travel suspended, leaving thousands stranded.
In Taiwan, one person was killed in an accident in a swollen river in eastern Hualien County.Â
Taiwan's weather bureau issued wind and rain warnings on Thursday for the southern and eastern part of the island, including the major port city of Kaohsiung where businesses and schools were closed and landslide warnings issued.
All domestic flights and ferry lines were suspended in Taiwan while more than 100 international flights were cancelled or delayed. Railway services between southern and eastern Taiwan were shut.
More than 5,700 people were evacuated as a precaution, mostly in the mountainous southern and eastern Taiwan, where more than 0.7 metres of rainfall was recorded in some areas and up to one metre of rain was forecast.
The storm had cut power from more than 49,000 households across Taiwan but the majority of them had since been restored.
"Typhoon Doksuri should not be underestimated," Kaohsiung city mayor Chen Chi-mai said in a Facebook post.
"The police and military force will assist in the effort of forced evacuation if needed," he said, highlighting threats by torrential rain in mountainous areas.
Braving occasional showers and winds, Taiwan's armed forces pressed ahead with a large-scale anti-landing drill on a beach near the major Taipei Port just outside the capital, simulating the repulsion of an enemy force with ground troops and tanks amid high military tensions with neighbouring China.
The storm has disrupted parts of Taiwan's main annual Han Kuang exercises and air-raid drills that started on Monday, as authorities cancelled some exercises citing safety concerns and the need to make preparations for the typhoon.
with Reuters
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