Abstract: Abstract: Physiological and biochemical effects of 4 cold resistant seed-coating agents(HET、YKJ、YKZYJ and ABA seed coating agent )on two early rice varieties were studied under chilling stress．The result showed that，under chilling stress，cold resistant seed coating agents maintained a rather high level of root vigour, POD, CAT and SOD activities and chlorophyll content, retarded the decline of soluble protein, reduced MDA content and electrolyte leakage, accumulated a great deal of soluble sugar and free proline, and decreased plant damage rate by a big margin, indicating that the cold resistant seed coating agents improved the ability of rice seedlings in resisting to chilling stress. Efficiency of cold resistance of YKZYJ was the best among the four cold resistant seed-coating agents tested. Key words： Rice; Cold resistant seed-coating agent; Chilling stress; Physiology and biochemistry, Mechanism of cold resistance