Using 24 northeast rice cultivars as teat materials and imitating low temperature stress treatment inthe rice tillering stage in the artificial climate chamber, effects of low temperature stress on yield and photosyntheticcharacteristics of northeast rice cultivars were studied. The results showed leaf net photosynthetic rate（Pn）, stomatalconductance（Tr）, transpiration rate（Gs） of different cold tolerance rice cultivars were declined under low tempera-ture stress, and the extent of decline was low resistance cultivars ＞ medium resistance cultivars ＞ high resistancecultivars. The intercellular CO₂ concentration（Ci） increased under low temperature stress. As to the rice yield andcomposition factors, panicle number per hectare, grains per ear, seed rate and 1000-grain weight decreased underlow temperature stress, the order of influence on the yield indicated panicle number per hectare＞ grains per pani-cle ＞ 1000-grain weight, which was especially obvious on the weak cold-resistant varieties.