18:00。 According to Chengdu local treasure's information, Dujiangyan Blue Tears turns on the lights at six o'clock in the evening and turns off the lights at eight o'clock. Dujiangyan, located on the Minjiang River in the west of Chengdu Plain, Sichuan Province, was built in the 3rd century. It was a large-scale water conservancy project built by Li Bing, the prefect of Shu County of Qin State, and his son during the Warring States Period in China.