Abstract: A numerical solution method for the transmission line equation based on the combination of the precise integration method and the time-domain differential quadrature method is proposed. First, the transmission line equation is spatially discretized by a fourth-order difference scheme based on the compact finite difference method, and the first-order linear ordinary differential equations about time are obtained. The fourth-order difference scheme has good approximate accuracy for spatial differentiation. Then, the precise integration method and differential quadrature method are used to numerically solve the first-order linear ordinary differential equations. Through theoretical analysis, compared with the traditional numerical solution method for transmission line equations, finite difference time domain(FDTD), this proposed method does not involve state matrix inverse operations, guarantees the accuracy of the numerical solution, and its numerical stability has nothing to do with the calculation time and space step. It can be used numerical calculations with large steps can effectively improve calculation efficiency. Finally, a simulation example is used to verify the algorithm. The results show that compared with the finite difference time domain method, this proposed method can suppress numerical oscillations and improve the calculation accuracy.