10%。 By adopting time averaged N—S equations and RNG k—ε model，the impeller-volute coupling characteristics were simulated by using SIMPLEC algorithm. The 3—D turbulent flow in centrifugal pump impellers with and without splitter blades were simulated under the different flow rates. When adding splitter blades，the results show that it can effectively control the reflux and flow separation at the impeller outlet. In comparison with performance prediction and experiment，the maximal error between performance prediction and experiment result is no more than 3% under the design flow rate，while 10% under the off-design flow rates.  