A number of rubber cement dosage specimens that rubber powder dosage different were obtained using same cement， water and fine aggregates， by adjusting the dosage of rubber powder. Then it was used to research the influence of rubber powder dosage on performance of cement mortar by measuring its liquidity， strength and toughness. The results show that: when water-cement ratio was equal and rubber powder replacing the same volume sand， the fluidity of cement mortar almost linear increased with rubber powder dosage increasing. With dosage of rubber powder increasing， compressive strength and flexural strength of 7 days and 28 days of cement mortar reduced， but toughness and wear resistant present linear growth trend when dosage of rubber powder less 30%.