Abstract: This paper observed the effects of several factors on the transformation of miracidia of Schistosoma japonicum and on the culture of young mother sporocysts of S. japonicum in vitro. The results showed: Different media(RPMI 1640, Tc 199, BME, and half strength RPMI 1640)and different serums(calf, sheep, rabbit, and "O" type human serum)did not affect the transformation. The longest survival seen in half strength RPMI 1640 was 48 days. The development of germinal balls was observed. The length of some parasites was nearly doubled, at 164μm. The serum of rabbit was most beneficial to the survival of the parasites. Galactose and DTT could not promote the transformation and the survival. Citrate, -ketoglutarate, malate and sodium succinate were not helpful to the survival of parasites. They inhibited the transformation and the effect of citrate was significant. The process of miracidial transformation in vitro was discribed and the ways of carbohydrate metabolism in mother sporocysts were discussed. Authors suggested "Latin square" as an optimum design in studying the composition of medium.