To investigate the effect of limited irrigation (W0, 0 mm, W1, 200 mm, W2, 400 mm, W3, 600 mm) and nitrogen (N0, 0 g/plant, N1, 75 g/plant, N2, 150 g/plant, N3, 300 g/plant) on yield, quality and water use efficiency of four–year–old Jatropha curcas L. in Yunnan dry–hot valley by using variance analysis and principal component analysis. The results showed that with increasing irrigation, the fruit yield, one hundred fruits weight and the water use efficiency of Jatropha curcas L. were first increased and decreased. Among the different irrigation treatment, treatment W2 showed the highest fruit yield, one hundred fruits weight and water use efficiency of Jatropha curcas L.. With the increase of nitrogen application, the yield, one hundred fruits weight and water use efficiency of Jatropha curcas L. were increased first and then decreased. Among the different nitrogen treatments, treatment N2 showed the highest yield, one hundred fruits weight and water use efficiency of Jatropha curcas L. The yield, one hundred fruits weight and water use efficiency of Jatropha curcas L. with W2N2 were the highest, and the principal component analysis showed that the W2N2 had the highest comprehensive score and the best nut quality of Jatropha curcas L..