Functional proteins in larvae of Bactrocera dorsalis, a major fruit pest, play a central role in their resistance to organophosphorus insecticides. Changes in proteins in B. dorsalis larvae after trichlorphon treatment may have a role in the resistance response to trichlorphon. We analyzed 14 protein spots of crude proteins from B. dorsalis larvae post-treatment with trichlorphon in two-dimensional gel electrophoresis through mass spectrometry and protein sequencing. We found functional proteins that are responsible for signal transduction (pkaap and dual specificity tyrosine-phosphorylation-regulated kinase), immunity (hemolectin), synthesis and decomposition (twinstar, cathepsin B,RE66325p), oxidative stress metabolism (glutathione S transferase and CG7320), energy metabolism (Act57B), and cytoskeleton formation (actin). These proteins appear to be involved in the resistance response to trichlorphon.