The Gaopoling Reservoir Earth-filling Dam was built on the strong seeping sand and gravel with extremely seepage. The supply pumping plant of Huaneng Power Plant first new project (2×350 MW) in Hainan Province Dongfang City will be built at about 120 m above the left side of the dam and the engineering construction make use of blasting. In order to ensure the safety of the project, the safety monitoring system at Gaopoling Reservoir Dam site was set up for the real-time monitoring during the period of the construction blasting. During the period of 54 days, the results of the artificial inspection indicated that there was no significantly abnormal phenomenon of dam deformation and seepage to be found; monitoring results showed that the changes of dam deformation and dam foundation seepage pressure were very small. It could be judged that the blasting construction in the reservoir area does not cause dam damage, and the program of the construction blasting controlled by the single hole charge volume within 30 kg is appropriate.