In this study,the efficiencies of a pre-dam complex system for non-point source pollution control was investigated for the management of the Tangma Reservoir in Liyang City,Jiangsu Province.The pre-dam complex is composed of settling area (A), shallow-water area (B),deep-water area 1 (C),deep-water area 2 (D),surface flow wetland (E),and biological membrane purification area (F).The results showed that the pre-dam complex system under the study contributed to significant improvement in the quality of agricultural non-point source pollution flowing through the pre-dam.The removal of TN,TP,COD_Cr could be up to 67.2%,68.2% and 89.3%,respectively,when the retention time was 1 d.The removal efficiency was increased with increasing of retention time,while the increment was small and stable.Moreover,increased areas (E and F) could significantly improve the removals of SS,TN,TP and COD_Cr,particularly the smaller SS which was consisted of size less than 15 μm.Furthermore, based on laboratory results,it was suggested that the retention time be 2-3 d in the Tangma project,and the system be optimized to improve the purification efficiency and high utilization of the area.