Shengsi County, under the Zhoushan City of Zhejiang Province, is located in the east of Hangzhou Bay, the Yangtze River estuary southeast, is the most eastern part of Zhejiang Province, Zhoushan Islands the most northern island county.Shengsi County is a subtropical maritime monsoon climate, four distinct seasons, winter without cold, summer without heat, sufficient light, temperature difference is small, between the north latitude 30°24 '~ 31°04', east longitude 121°30 '~ 123°25' between.

Shengsi County is composed of 404 islands, of which 16 inhabited islands, a total area of 8824 square kilometers, including land area of 86 square kilometers, sea area of 8738 square kilometers. By 2018, Shengsi County has jurisdiction over 3 towns and 4 townships, and the county government is stationed in Caiyuan Town. According to the seventh census data, the permanent resident population of Shengsi County is 66,903 people by midnight on November 1, 2020.

According to "Shiji" and "Shui Jing Notes" records, ancient times, Shengsi land for Nanman, East Yi island Yi land. In October 1949, Shengsi County, belongs to the mainland exile county Wolfqi Island of Jiangsu Province government jurisdiction. In March 1987, change Zhoushan area for Zhoushan City, Shengsi County is Zhoushan City. Shengsi Islands scenic area is the integration of Marine culture and island folk customs, to sightseeing, leisure vacation and science and education activities as the main function of the island national key scenic area.

Shengsi County is one of the first and second batch of pilot areas of Zhejiang high quality development and construction of common prosperity demonstration zone. In 2020, the GDP of Shengsi County was 11.65 billion yuan, calculated at comparable prices, an increase of 2.1% over the previous year. The value added of the primary industry was 3.52 billion yuan, that of the secondary industry was 1.96 billion yuan and that of the tertiary industry was 6.17 billion yuan, up 3.5 percent, 4.3 percent and 0.7 percent over the previous year respectively. The tertiary industrial structure is 30.2:16.8:53.0. Based on the registered population, the per capita GDP was 157,384 yuan, equivalent to US $22,817 at the year-end exchange rate (6.8976). The added value of the Marine economy accounted for 78.2% of GDP.