The three-dimensional structure of thermostable catechol 2,3-dioxygenase(TC23O) from Bacillus Stearothermophilus has been modeled basing on the known x-ray structure of catechol 2,3-dioxygenase(metapyrocatechase) from Pseudomonas putida mt-2, using computer graphics energy minimization techniques. The rationality of the resulting model was validated by Ramachandran plot and Profile-3D. The structure-functionally important residues, such as M⁺⁺ binding residues and the substrate binding residues, were identified from the model. These residues are candidates for further site-directed mutagenesis experiments. The reason that the thermostability of TC23O is greater than metapyrocatechase(MPC) has been found, which may be due to the specific structure of the TC23O in the C-end mainly.