Objective To clarify the feeding preference and growth adaptability of Spodoptera frugiperda on sugarcane and Rottboellia cochinchinensis.Method Two sugarcane varieties (‘Guitang 42’ and ‘Taitang 22’) , two fruit cane varieties (‘Guiguozhe 1’ and ‘Yellow skin sugarcane’) , and a common weed of R. cochinchinensis in sugarcane field were selected as the research objects. Through the feeding preference experiment and constructing the life table of the experimental population, the feeding preference and growth adaptability of S. frugiperda on sugarcane and R. cochinchinensis were studied. Result The larvae of different instars of S. frugiperda preferred to feed on fruit sugarcane when choosing between sugarcane and fruit sugarcane, and the feeding selection rate on ‘Guiguozhe 1’ was most significantly higher than those of other tested varieties. The larvae of S. frugiperda had a significant feeding tendency to R. cochinchinensis when choosing between ‘Guiguozhe 1’ and R. cochinchinensi. The larval survival rate of S. frugiperda on R. cochinchinensis was the highest, which was 66%, followed by 12% on ‘Guiguozhe 1’. On other sugarcane varieties, S. frugiperda had died in the period of low instar. The life cycle of S. frugiperda could be completed on R. cochinchinensis, and the intrinsic rate of increase (r_m) and finite rate of increase (λ) were 1.16 and 1.52, respectively. Conclusion Compared with sugarcane, S. frugiperda preferes to feed on R. cochinchinensis and has higher adaptability.