In order to make use of the abundant brackish water underground reasonably in gravel－mulched field area of Ningxia，taking the NO．5 Cerasus humilis as the test material，the influences on photosynthesis and yield were studied through the brackish water irrigation test with 2．35 and 4．07 g /L mineralization degree． The results show that: the photosynthesis and yield of the 2．35 g /L treatment is superior to that of the 4．07 g /L treatment，but the fruit quality of the 4．07 g /L treatment is better; there is no significant difference of SPAD，single fruit weight，yield per mu and irrigation water use efficiency of Cerasus humilis between the 2．35 g /L brackish water irrigation treatment and the fresh water treatment，while the fruit quality irrigated by 4．07 g /L brackish water is remarkable superior to that irrigated by fresh water． Considering all indexes，it can be concluded that the 2．35 g /L salinity is the suitable salinity for local brackish water irrigation，at the same time，it is also feasible to use the local 4．07 g /L brackish water as irrigation water．