The invention relates to a finite element simulation method capable of removing a microwave tube high-frequency circuit in a pseudo-DC mode, comprising the flowing steps: (A) using a zero electric displacement vector as an electric field constraint equation and acquiring an integrated form of the electric field constraint equation according to an boundary value problem of an electromagnetic field in a microwave tube high-frequency circuit and acquiring a functional equation of the boundary value problem of the electromagnetic field through a standard variation principle of a finite element method; and (B) necessarily ensuring the match between grids on a main surface and grids on a secondary surface on a peripheral boundary when solving a solution domain and considering a pseudo-periodic boundary condition by adopting a dissection solution domain of tetrahedral grids. The invention has the advantages that the finite element simulation method can greatly improve the accuracy, the efficiency and the robustness of microwave tube high-frequency system simulation.