Abstract: 【Objective】 The purpose of this study was to provide a theoretical basis for ecological control and sustainable control of Scotogramma trifolii, in order to determine the selection preference of host plants and population fitness of Scotogramma trifolii. 【Method】The oviposition selection rate, larval feeding rate, growth and development index and population parameters were investigated by field cage experiment and indoor feeding experiment. 【Result】The oviposition selection rate of Scotogramma trifolii was Chenopodium album L. > cotton > sugar beet > Chinese cabbage, larva feeding selectivity from high to low was sugar beet > Chinese cabbage > Chenopodium album L. > cotton. The larval duration of the four host plants was cotton > sugar beet > Chinese cabbage > Chenopodium album L., and pupal duration was cotton > sugar beet > Chenopodium album L. > Chinese cabbage. The pupa weight of Scotogramma trifolii fed with Chinese cabbage, cotton was slightly heavier than that fed with Chenopodium album L., sugar beet. The hatching rates of Scotogramma trifolii fed with four host plants were between 81.97% and 87.26%. The larvae fed with Chenopodium album L. had the highest survival rate (82.93%), while those fed with cotton had the lowest survival rate (22.50%). The pupae of Scotogramma trifolii fed with cotton had the highest survival rate (100.00%), while those fed with sugar beet had the lowest survival rate (82.36%). The eclosion rate of Scotogramma trifolii fed with Chenopodium album L. was the highest (91.36%), while that fed with sugar beet was the lowest (71.38%). The fecundity of Scotogramma trifolii fed with Chinese cabbage was the highest (367.30 eggs / female), while those fed with cotton were the lowest (274.70 eggs / female). 【Conclusion】Cotton, Chinese cabbage, sugar beet, and Chenopodium album L. are hosts of Scotogramma trifolii. Chenopodium album L, Chinese cabbage and sugar beet are the suitable hosts for Scotogramma trifolii. Chenopodium album L. is the most preferred host for oviposition, sugar beet and Chinese cabbage are the most preferred hosts for larval feeding. The oviposition preference of Scotogramma trifolii is not consistent with that of feeding choice. Feeding four hosts had no significant effect on egg duration, adult duration, hatching rate and fecundity, but had significant effect on larval duration, pupal duration, generation duration, larval survival rate, pupal survival rate, eclosion rate and pupa weight. There were some differences in the fitness of Scotogramma trifolii to different host plants.