Objective To investigate the mechanical property and tooth canal structure changes after RCT. Method Three-Dimensional Finite Element model of tooth and centerline of tooth canal were constructed to research into the mechanical property and tooth canal structure, respectively. Result Three-dimensional finite element model and centerline model were separately constructed and made the comparison for the changes of mechanical property and tooth canal before and after RCT. Conclusions The method could be used to fast set up three-dimensional finite element model of tooth and centerline model and used for all kind of tooth to analyse their biomechanics properties.