Abstract: The response of photosynthetic functions of winter wheat to salt stress was studied in this paper The results showed that the chlorophyll content per unit area of leaves, the capacity of light energy absorption of the chloroplasts, the electron transport rate of PSII, the efficiency of primary conversion of light energy and the coefficient of photochemical fluorescence quenching (qP) were greatly reduced by salt stress, especially NaCl of high concentration (400 mmol/L) At the same time, photosynthetic oxygen evolution rate and its light saturation point was decreased, and photoinhibition was exacerbated by salt stress These results accelerated the decrease of the capacity of oxygen evolution and carbon assimilation Therefore, plants could not effectively accumulate photosynthetic products This is one of the important physiology causes of low yield of crops grown in saline alkali soil