4 japonica rice varieties with different quality were used in this experiment.The relationship between dynamic changes of chalkiness formation in vigorous and weak grains and grain filling rate at later growing stage ware studied.The results showed that:Dynamic changes of chalkiness formation of vigorous grains in rice were mainly during 5～15 d，15～30 d after heading, but at other stage the change of chalkiness degree was not clear.The dynamic changes of chalkiness formation of vigorous grain in japonica rices of different quality were of great difference.Dynamic changes of chalkiness formation of weak grains in rice were mainly during 10～35 d,35～40 d after heading,but after that the change of chalkiness degree was not clear.The chalkiness degree of weak grains in good quality rice varieties balanced as mature 35 d after heading,while that in bad quality rice varieties balanced as mature 40 d after heading.Formation period of chalkiness degree and the ending period of grain filling were consistant and completly synchronous in either vigorous or weak grains of japonia rices with different quality.