【Background】In China, genes of Bt cotton mainly express Cry1Ab or Cry1Ac proteins. Until now, few new Bt genes have not be studied as potential used topest control pests. However, large-scale cultivation of Bt cotton will most likely increase the possibility of pests to become resistant against these types of Bt cotton. It is necessary to examine the responses of cotton bollworm to other Bt proteins. 【Method】Using a diet incorporation method, we evaluated the toxicity of six types of Bt proteins (1.0 μg·g-1) against cotton bollworm′s larval growth and development. 【Result】The results showed that the LC50 of Bt proteins to neonate larvae of cotton bollworm were Cry1Ab (0.065 μg·g-1), Cry1Ac (0.074 μg·g-1), Cry2Ab (0.133 μg·g-1), Cry2Aa (11.67 μg·g-1), Cry1Ah (13.010 μg·g-1) and Cry1Ca (＞20 μg·g-1). When a concentration of 1.0 μg·g-1 was applied, Cry1Ab and Cry1Ac had the strongest effects among the six Bt proteins followed by Cry2Ab. There were no difference between Cry1Ah and Cry2Aa effects on first-instar larval mortality and weight reduction. However, there were significant differences between these two proteins at the second-instar larvae. There were no significant differences between Cry1Ah and Cry2Ab in terms of body weight and growth rate of cotton bollworm second-instar larvae. Cry1Ca has almost no effect on the survival rate, growth and development of cotton bollworm when compared with the control. 【Conclusion and significance】The LC50 of Cry1Ah， Cry2Aa and Cry2Ab are comparable to Cry1Ac and Cry1Ab. They could be used as an alternative strategy to control cotton bollworm larvae.