Abstract: Five varieties of ‘Shanli’‘Pingxiangli’‘Hanhongli’‘Hansuli’and ‘Shanli’（Pyrus ussuriensis） were used as test materials, the field freezing injury investigation method and chlorophyll fluorescence test method were used.The effect of diurnal variation of leaf chlorophyll fluorescence parameters in autumn on cold-resistance of pear varieties in winter was studied, in order to provide reference for rapid identification of cold resistance of pear varieties and high-quality cultivation of pear in cold regions of northern China.The results showed that light energy conversion efficiency of cold-resistant pear varieties in autumn was in the order of ‘Shanli’＞‘Nanguoli’＞‘Hanhongli’＞‘Pingxiangli’＞‘Hansuli’ from strong to weak.The differences among Fo, Fv, Fv/Fm and Fv/Fo varieties were extremely significant.Fo, Fv, Fv/Fm and Fv/Fo varied greatly among varieties, Fo values showed an inverted ‘V’ shape, Fv value of different varieties fluctuated slightly in different time periods and showed an overall upward trend, Fv/Fo value was almost consistent with that of Fv/Fm.At absolute low temperature of-31 ℃,the order of cold resistance of cultivars was ‘Hanhongli’＞‘Hansuli’＞‘Pingxiangli’＞‘Nanguoli’＞‘Shanli’,the cold tolerance was negatively correlated with diurnal Fo and positively correlated with diurnal Fv/Fm.