At present， most of the synchronization devices regulate the frequency and voltage by adjusting the speed and exciting current of the generator， which can only be used in power plants. Based on the power exchange principle， a new fast method of power grid synchronization is proposed. It can be combined with existing technology of STATCOM to form a new compound system， which has the two functions: power grid synchronization and reactive power compensation. As a power grid synchronization device， the main advantages include fast synchronization speed and operational simplicity. It can be used to achieve power grid synchronization and ring net parallel operation. Under normal operating condition， it can be used for reactive power compensation so as to avoid unnecessary waste of installed asset. Simulation results demonstrate the method is effective.