In order to study the changes of photosynthetic characteristics and yield traits after experiencing low-temperature freezing injury, an experiment with Zhoumai 22 as research object was carried in Shangqiu of Henan province.It was designed for two growth stages (the early jointing stage and late jointing stage) and set five temperature levels seperately (-1℃、-3℃、-5℃、-7℃、-9℃) in artificial intelligence frost box. The photosynthetic characteristic and chlorophyll SPAD value, were measured after 4 hours’ treatment under low temperature, and the changes of wheat plant character was measured after harvest. The result showed that at the early jointing stage and late jointing stage, and with decreasing of temperature, the photosynthetic rate of wheat A, inter-cell CO2 density Ci, leaf transpiration rate E and stomatal conductance GH2O reduced gradually. But under -7℃ treatment they were significantly lower than CK when temperature decreasing at the early jointing stage. While the A, Ci, E and GH2O value under -5℃ treatment were significantly lower than CK when temperature decreasing at the late jointing stage, then returned to normal after 3 days under different temperature levels. When temperature decreased below -9℃ at the early jointing stage, SPAD values were significantly reduced, but at the late jointing stage SPAD values were significantly reduced when temperature decreased below -5℃. When low temperature was delayed, small tillers spike height and spike length were shortened, and grain number and 1000-grain weight were decreased, but plant height and spike number per plant increased. With temperature decreasing, small tiller spike height, plant height and grain number per spike significantly decreased. The biological yield and grain yield of wheat significantly decreased after low-temperature freezing injury occurred.