[Aim] Octodonta nipae and Brontispa longissima both are important invasive pests of palm trees; they both have similar morphologies, feeding sites and cause similar damage characteristics. The study of the host selectivity of these two pests can help understand the mechanisms of spread and outbreak.[Method] In the laboratory, two host plants, Cocos nucifera and Phoenix sylvestris, were used to rear O. nipae and B. longissim. Survival rate, egg production, developmental duration, and preference of the two kinds of host plants by O. nipae and B. longissim were studied.[Result] O. nipae survival on the two host plants significantly differ, expect at egg and pupal stages. Larval survival of each instar feeding on P. sylvestris was higher than on C. nucifera. B. longissim survival feeding on C. nucifera was higher than on P. sylvestris, with means values of 95% and 86%, respectively. The probability of eggs laid by of O. nipae feeding on P. sylvestris was 0.23, while no eggs were laid when feeding on C. nucifera and thus not completing a full generation. The probability eggs laid by B. longissim feeding on C. nucifera was 0.86 while no eggs were found on P. sylvestris. When O. nipae fed on P. sylvestris, the experimental index of population trend was 12.55, and B. longissim feeding on C. nucifera, the index was 66.55.[Conclusion] O. nipae and B. longissima have obvious preference between the two host plants. In Hainan, far more C. nucifera are available than P. sylvestris. Our results could explain the widespread outbreak of B. longissima in Hainan, as well as the occasional occurrence of O. nipae.