The effects of different photoperiod treatments (6, 8, 10 and 14 h/d) on the plant growth, endogenous hormones contents, and sex differentiation of luffa (Luffa cylindrica Roem.) seedling were studied by artificial shading method, which will provide the theoretical basis for artificial light regulation of this plant species. The results showed that: (1) with the extension of the photoperiod, the plant biomass was increased gradually. The total Chl a+b contents, SOD, POD and CAT activities, soluble sugar, soluble protein and free amino contents were first increased, then decreased, and reached to maximum under the treatment of 10 h/d. (2) The GA₃, IAA, ZT contents of 8 and 10 h/d were lower than those of 6 and 14 h/d, the ABA contents were the contrary. (3) The 1^st female and male flowers of 10 h/d were the lowest, the number of female flowers and yield were the highest of all photoperiod treatments. Overall, 10 h/d photoperiod was more beneficial to the growth and cultivated health seedling of luffa.