Abstract: 【Objective】Jatropha curcas L. is an important biodiesel tree in Southwestern China. The floral characteristics of J. curcas might have different effect on the behavior and visiting frequency of its pollinators which make contribution to its reproductive success.【Method】This paper studied the floral syndromes of both female and male flower of J. curcas, and tested the effect of floral constituents, petal size and stamen color on visiting frequency of honey bees and flies to the flower of J. curcas. 【Result】The corolla diameter of male was significantly smaller than that of female flower, while the diameter of stamen was significantly larger than that of pistil of J. curcas. This might influence the preference of pollinators to male and female flower. There was no significant difference between height of stamen and that of pistil, which will help pollinators to transfer pollen grains from pistil to stigma easily. There were strumaes on the surface of pollen grain, and small hollows on the surface of stigma, which can emit a little mucus. These microtraits will help pollen grain adhere onto stigma easily. Both the removing of stamen and petal could significantly reduce the visit frequency of bees and flies to the flower of J. curcas. The removing of calyx did not change the floral attractiveness of J. curcas to both bees and flies. The reduction of petal size also could significantly reduce the visit frequency of bees and flies. Color change of stamen did not affect the visiting frequency of flies, but significantly reduced that of honey bees. 【Conclusion】There is significant difference between floral characteristics of male and female flowers of J. curcas. Honey bees and flies show significant difference in identifying the floral constitute, petal size and floral color of J. curcas.