The invention discloses a STATCOM (static synchronous compensator) control system adopting a droop control strategy and a control method thereof. The STATCOM control system adopting the droop control strategy comprises a direct-current side capacitor, a three-phase inverter bridge and an inductance-capacitance filter, wherein the direct-current side capacitor and the three-phase inverter bridge are connected in parallel and then connected with the inductance-capacitance filter, and the inductance-capacitance filter is connected to a PCC (Point of Common Coupling) of a power grid by a three-phase switch K through a coupling transformer T. The control method disclosed by the invention comprises the steps of real-time signal collection, computation of active power reference value P*, computation of reactive power reference value Q*, computation of frequency reference value omega* and voltage modulation amplitude reference value E*, computation of phase reference value Delta* and computation of voltage modulation signals; and only one PI (proportional integral) regulator and two droop control coefficients need to be regulated, thus the whole control method is easy to realize, and further the power system can better supply power to users safely, excellently and economically.