Abstract: Plant flowering and breeding characteristics are important to understand rep roduction of p lant population.Flowering characteristics and pollination ecology of Jatrapha curcas were investigated in Yuanjiang County, YunnanProvince. The breeding system, pollen-ovule ratio ( P /O) and pollen viability were determined. The results were asfollows: (1) Jatropha curcas wasmonoecious, The p lant p roduced flowers in dichasial inflorescences. Normally, theflowers were unisexual, and male and female flowerswere p roduced in the same inflorescence. In a few, onlymaleflowerswere p roduced in an inflorescence, and fruitwere p roduced only through pollination between different flowersfrom the same or different p lant. The 1 ife span of the male flowerwas about 2 days. The life span of the female flower was about 5～12 days. The diameter of female flowerwas bigger than that of the male flower slightly. (2) The pollen viability ofmale flowerwas relatively high in 9 hours after blooming and get low 33 hours later. The pollen hardly had any viability after 48 hours. The stigmatic recep tivity of female flowerwas strong during 1st -4th day and beganto decline on 5th day. On 9th day, stigma comp letely lost its recep tivity. (3) The effective pollination way of J. curcas was insect pollination. (4) J. curcas was out-crossing, partly self-compatible, requiring pollinator.