Kernel naturally dry-down rate of 23 corn hybrids with different maturity period in ten days after physiological maturity period were analyzed in this paper.The results showed that the kernel water contents were between 31.96% and 43.60% during physiological maturity period.The differences of kernel naturally dry-down rate in corm hybrids were significant,whose variations were between 0.18% and 1.80%.The correlation between kernel naturally dry-down rate and physiological maturity stage were insignificant.The rates were affected mainly by kernel water contents in physiological maturity stage of corn hybrids.