Cavitation is one of the main causes that jeopardize the steady operation of high speed centrifugal pump. An inducer installed in the upsteam of the impeller is an effective method to improve the cavitation resistance performance of the pump. In order to investigate the evolution process of cavitation in a low-specific high speed centrifugal pump with inducer, the visual experiments of cavitating flow in impeller and inducer passages were carried out by high speed photography. And the internal flow characteristics of the centrifugal pump were analyzed by CFD technology. The experimental results showed that cavitation inception occurred near the blade leading edge of inducer when ΔH was 5.0m, which was mainly caused by the tip leakage vortex. In the process of cavitation development (1.07m<ΔH<5.0m), cavitation phenomenon was very complex in which tip leakage vortex cavitation, sheet cavitation and cloud cavitation could be observed in the blade passage of inducer. Also it was found that asymmetric cavitation as one type of cavitation instabilities occurred when net positive suction head was lower (ΔH was 1.5m). Both in the periods of cavitation inception and development, the head and efficiency of high speed centrifugal pump with inducer basically remained the original data. The backflow vortex cavitation occurred at the inducer inlet near the shroud in the period of cavitation deterioration (ΔH<1.07m). Meanwhile, the bubble generally blocked the whole passage of inducer and spread to the impeller passage that resulted in breakdown of the head and efficiency in high speed centrifugal pump with inducer.