The present invention discloses a method and a system for controlling stabilization of a flexible direct current and weak alternating current power grid, belonging to the field of electric power systems. The method comprises the steps of: determining positions of an operating point at an alternating current power grid power transmission feature curve Us-Ps and a flexible direct current power feature curve Us-Pc; determining the positions of the operating point, wherein different conditions of the operating point being located at a Us-Pc continuous change interval, the operating point being located at a Us-Pc forced recovery interval or having no an operating point are included; when a flexible direct current and weak alternating current power grid series-parallel system has not steady-state operating point or the voltage Us of the operating point is lower than a set threshold value Usth, resetting a FRTS (Fault Ride Through Strategy) parameter IcdF; monitoring an operating state of thedirect current and weak alternating current power grid series-parallel system after fault disturbance is generated in real time, and when the dynamic unsteadiness is caused by current recovery, stopping increasing of the icd and the icq; and if Us is still lower than the Usth and the duration exceeds Ts, falling back a direct current power [delta]Pc to improve the Us, wherein FD is a tag bit usedfor avoiding current perturbation control frequent motion. The stable operation of the series-parallel system can be recovered.