The invention provides a transient response analytic calculation method for a high-voltage direct current power transmission system. The method comprises the following steps that: A, a smoothing reactor, a direct current filter and a direct current power transmission circuit of the high-voltage direct current power transmission system are combined with a voltage current relationship to obtain a differential algebraic equation set of the high-voltage direct current power transmission system under different operation work conditions according to a circuit principle; according to the logic relationship of a control system, a differential equation of the control system is built, and a state equation (shown as the accompanying drawing) of the high-voltage direct current power transmission system is finally formed, wherein the differential algebraic equation set is a constant-coefficient nonhomogeneous linear differential equation set, x is the state quantity under the i-th operation work condition, Ai is a state matrix, Bi is an input matrix, the input u(t) is a rectifier-side and inverter-side three-phase voltage instantaneous expression, and Ci is a component after the addition of the control system; B, through the steady state response calculation on the high-voltage direct current power transmission system, the relationship x(t) of the state quantity of the high-voltage direct current power transmission system varying with time and initial values of each operation quantity of the control system are obtained; C, under the alternate current voltage change, the direct current transient response calculation is carried out; and D, the calculation is completed.