Abstract: Based on the continuous monitoring of 27 indexes in Huangqian Reservoir, the drinking water source of Taian city from 2001 to 2002, the water quality was appraised according to the environmental quality standards for surface water(GB3838-2002) and single gene standard which were rather common used in China. The results showed that the main factors influencing the reservoir's water quality were permanganate, chemistry needed oxygen capacity, the total phosphorus and nitrogen, the water quality in flood season was worse than that in non-flood season, and the water quality of storeroom was better than that of dam-former. On the base of those, the reasons were analyzed, the corresponding settlement measures were put forward, and the scientific basis were offered to protect the drinking water source pointedly, improve water quality further, and optimize water management.