Abstract: Random sampling and tracking investigation were applied to determine comparatively the floral quantity, size and the fruiting rate of Jatropha curcas during the first two flowering of semifield in different site conditions. The results showed that, male inflorescence usually produced on the old branches, and polygamous inflorescence produced on the 1yearold twigs. The number of polygamous inflorescence is 1.8—17 times than that of male inflorescences. There are a few female flowers, usually varies from 1 to 25 per inflorescence, and a large number of male flowers, usually 10—20 times than that of the female ones within polygamous inflorescences. The fruiting rate of J.curca is relatively stable and high, commonly more than 90 % higher than the average, and the number of seeds per fruit set varies from 2.6—2.9. Site conditions and flowering order could significantly affect the number of male inflorescence, polygamous inflorescence, and the number of male and female flowers within polygamous inflorescence. It would be a very useful strategy of reproduction for J.curcas to produce a large number of polygamous inflorescences, for that it could ensure the female function strengthened, and the suitable function of male inflorescence and male flowers in polygamous inflorescences were probably more important than that of reproduction. The flora size and the environment of pollination of J.curcas were closely related, and a large amount of male flowers were very useful to attract pollinators.