To research the thermal behavior of Caenorhabditis elegans (C.elegans), a new method was proposed to model and simulate the thermal behavior of C.elegans based on the artificial neural network. Firstly, the motion model of the nematode was established. Then, a nonlinear function was designed to approximate the movement logic of the thermotaxis of the nematode. Thirdly, the speed and the orientation change capabilities were implemented, and these capabilities had been realized by the artificial neural network. Finally, the experimental simulation was carried out in the Matlab environment, and the thermal behavior of the nematode was simulated. The experimental results show that Back Propagation (BP) neural network can simulate the thermal behavior of C.elegans better than Radical Basis Function (RBF) neural network. The experimental results also demonstrate that the proposed method can successfully model the thermal behavior of C.elegans, and reveal the essence of the thermotaxis of C.elegans to some extent, which theoretically supports the research on the thermotaxis of the crawling robot.