Abstract: Based on the analysis of field observation data, the mathematical calculation and the physical modeling, this paper studies and compares effect of the meandering channel and straight channel evolved in the Jianshan bend on the important environmental factors such as riverbed variation in the upper reaches of Qiantang Estuary, tide, current, tidal bore and salt water intrusion etc.It is more reasonable to adopt the meandering alignment according to the principle of reducing tidal influx and raising the ratio between river flow and tidal discharge, overall development of the multiple purpose, and eliminat ing the unfavorable factors which was shown in harnessing process of Qiantang Estuary.