Based on the ecological and environmental problems caused by water resource exploitation in Qiantang River basin,the conception and connotation of annual suitable eco-environmental water requirements in Qiantang River Basin are analyzed. Correspo ndingly,a computation model is constructed to calculate both channel eco-environmental water requirement and riverside eco-environmental water requirement. Results show that the annual suitable eco-enviro nmental water requirements of channel and riverside are1.59×10¹⁰and 6.70×10⁹m³/a,respectively. The total annual suitable eco-environmental water requirement amounts to2.26×10¹⁰m³/a.This research provides a scientific basis for eco-environmental protection,exploitation,and utilization of water resources not only in Qiantang River Basin but also in other similar humid basins.