Aimed at the phenomenon of too much evaporation of reservoir in inland arid area, the paper carried out the research on new anti-evaporation materials,which is beneficial to reduce invalid evaporation and improve the effective utilization of reservoirs. Through covering part of reservoir and figuring out the effective coverage of evaporation materials under different meteorological of full period, then according to the probability of anti-evaporation factors, it calculated the effective anti-evaporation capacity and verified the effect of water saving.Taking some reservoir in inland arid area as an experimental object, the paper only probed the problems that had experienced above.