This paper evaluates currently practicing operation method of Qingjiang cascade reservoirs system with recently introduced HEC-ResSim model.Suitable operation rules for cascade reservoirs operation were derived using HEC-ResSim model.Considering 1955-2005 runoff records

three representative years（wet

normal and dry） were selected and 3-hour time interval simulation was carried out.A parallel simulation and comparative study was performed.Simulation results show that the HEC-ResSim model is significant over conventional method during wet and normal years and flooding seasons in all aspects and no significant difference in dry year and non-flooding seasons.It can be concluded that HEC-ResSim is a better simulation tool for Qingjiang cascade reservoirs operation than the conventional method.