Based on the seismic monitoring network of the Dagangshan Reservoir，we established a detection system of active seismic source，including an Accurately-Controlled Routinely-Operated Seismic Source which weighs 10 tons，as well as 8 permanent stations,2 mobile stations and 1 source receiver station. In this paper，we introduce the basic information of the detection system，the source-groundsill coupling，the performance and its affecting factors. Also，the relative velocity variation in the Dagangshan reservoir area is obtained through the preliminary data processing.