Abstract: The larvae of Batocera lineolata fed with Juglans regia and Eucalyptus sp. were used to investigate the feeding choice behavior to J. regia and Eucalyptus sp. through the artificial replacement of new host, and measure the enzymatic activity changes of digestive enzyme, detoxification enzyme and protective enzyme by the spectrophotometer method before and after the replacement of new host. This study aimed to illustrate the effect of different host foods towards the feeding behaviors and internal enzymatic activity of B. lineolata, and further explore the host adaptative mechanism of B. lineolata. The result shows that the larvae of B. lineolata preferred feeding the original host, but forcing the larvae to feed the new host could decrease the tendency towards feeding the original host. Different hosts could significantly affect the internal enzymatic activities of digestive enzymes, detoxifying enzymes and protective enzymes in the larvae of B. lineolata. Activities of acetylcholinesterase (AchE) increased significantly, while tryptase (TPS), cellulose C_X enzyme (EG), polyphenol oxidase (PPO), glutathione-S-transferase (GSTs) and superoxide dismutase (SOD) decreased markedly after the replacement of new host. In conclusion, the larva of B. lineolata has a memory effect to the original host, and the replacement of host can dramatically impact their internal enzymatic activity. Acetylcholinesterase may make a difference in their adaptation to the new host.