In order to solve the contradiction between the computing precision and computing time, according to the THM(themo-hydro-mechanical) coupling mechanism and the domain decomposed method, the paper selects preconditioning conjugate gradient to solve paralleled solution of system equation, in which using mpi+177 establishes a master Islave model and the calculation of the governing equations is performed on the Hobai University high function computer, and this question is verified by one example .The conclusion showed that this method can obviously save the computing time and will be applied extensively in the future .