The finite element numerical calculation can get the shock wave velocity and overpressure at any point in the explosion field, but some factors such as the parameter value of the state equation influence the calculation results. The tomography inversion can acquire the velocity and overpressure distribution of shock wave; however, the initial model and constraints can affect the inversion results. Aiming at the shortcoming of the two algorithms, this article combines the two methods and presents a new algorithm to reconstruct the explosion field. First, The LS-DYNA finite element program is applied to establish a numerical model and calculate the shock wave velocity and superpressure in air explosion. Second, generalized inversion with regularization tomography inversion algorithm is used to invert the shock wave field. In the inversion, the finite element calculation results are used as the initial model of inversion and constrain the inversion. The experiment results prove that the proposed algorithm can greatly improve the inversion accuracy and the iterative convergence speed. The inversion image can better depict the internal details of the explosion field and eliminate noise.