The invention relates to a power flow determination method of an alternating current and direct current system containing multi-terminal high voltage direct current transmission. The method includes the following steps that the hybrid power system containing multi-terminal high voltage direct current transmission is decomposed; power flow computing is conducted on sub-systems in the decomposed power system, and feature data are determined; boundary parameters of a coordination layer in the decomposed power system are amended so as to achieve global convergence. The method makes full use of the advantages of distributed parallel computing in large power network analysis computing, power flows are computed by all alternating current sub-systems separately, the feature date of sub-regions are introduced into boundary points, and the boundary parameters are amended in the direct current coordination layer to achieve global convergence. By means of the method, the convergence of power flow computing of the alternating current and direct current hybrid system is improved, the computing speed of the alternating current and direct current hybrid system is increased, and the practical level of power flow computing software in the current actual power grid and future power grid is improved.