The invention discloses an impedance voltage source equivalent circuit design method for a doubly-fed generator under machine-side symmetric fault. The technical scheme adopted is that the method comprises the following steps: first, performing Laplace transform for voltage equations of a short-circuit doubly-fed induction generator under condition of neglecting resistance of a rotor and a stator; measuring machine-side fault voltage to determine voltage drop factors, and designing the voltage equations into the equations with two zero states and two zero input responses according to a physical process method; considering the attenuation function, obtaining an all-current analytic expressions of short-circuit current under voltage symmetric drop in different degrees according to solutions of four sets of equations; and finally measuring an original voltage value of the rotor, the rotational speed of the rotor, and an voltage initial phase angle of the stator at short-circuit moments, and designing the impedance voltage source equivalent circuit of the doubly-fed wind generator according to the all-current analytic expression. According to the invention, the obtained equivalent circuit can show the time-variation law of the short-circuit current under symmetric voltage drop at different moments.