Yucheng Subdistrict (in Chinese: 玉城街道), formerly known as Chengguan Town (城关镇), is a sub-district office under the jurisdiction of Yuhuan, Zhejiang Province, People's Republic of China.

In the sixth year of the Qing Yongzheng era (1778), when Yuhuan Hall was established, a city was built within the area, commonly referred to as Chengli (城里).

In January 1980, it was renamed Chengguan Town (城关镇) and incorporated the three townships of Qingma (青马), Shashan (沙鳝), and Huancheng (环城).

The Sanhetan Site is located in Nanshan Village under the jurisdiction of Yucheng Subdistrict, with a history dating back approximately 2800 to 2400 years.

Discovered in 1981 by local villagers during excavation activities, the site spans a period of 1800 years, providing rich data for the study of prehistoric cultures in the southeastern coastal islands of mainland China.