In the course of studying the artificial hatchely rearing of seacucumber Apostichopus japonicus, it was found that the survival rate of juveniles seacucumber was low. The period of development from seedling to juvenile was anothercritical phase in its life cycle. During this phase, the juvenile were mostr susceptible tothe adverse influence of their environment. The method of mathmatical statistics was applied to test the effect of severalfactors influencing the survival rate during the juvenile stage. Four factors wereselected, viz., settling density of seedling, types of feeds, temperature of the culturemedium, and the mode of water exchange. The results from the variance analysis anddirect observation indicated that settling density and types of feeds were more impor-tant than other two factors in fluencing the survival and growth rates of juvenilesea cucumber. A settling density of about 0.2 individuals/cm~2 was optimal, of 0.5individuals/cm~2 less favorable. A filtrate of ground Sargassum proved to be the bestfood for juvenile, and the next best was a mixture of ground Sargassum and Dicra-tina.