The actual working condition of marine propeller was simulated using a rotating disc experimental tester, and the variation of weight loss and mechanical property of tin brass under the interactive effect of cavitation and erosion was discussed through weight loss analysis, surface and cross sectional morphologies observation and mechanical property test. The results show that the incubation period is short for the weight loss of tin brass under the interactive effect of cavitation and erosion in test medium including 1 kg/m3 sand, in which the weight loss of tin brass mainly presents the rising period, the stable period, the decline period. When the concentration of sand reaches 2 kg/m3, the weight loss of tin brass is increased obviously at the same interactive period，and the stable period is not obvious. After cavitation and erosion, non directional short furrows and scaly pits are shown on the surface of tin brass, and meanwhile the significant work hardening phenomenon appears.