The Doppler frequency shift of the inter-satellite coherent communication system reaches the order of Gigahertz. At the same time, it is affected by the line width and phase noise of the tuning laser, which imposes high requirements on the optical phase-locked loop system. Based on Costas loop technology, an optical locked loop is achieved through inner and outer loops, and the local laser is tuned when the tuning of temperature, piezoelectric ceramics(PZT), and acousto-optic modulation device(AOFS) are compounded together. An experimental test system is set up to test the performance of the loops. It turns out that this system is capable of a phase locked range of 4 GHz and a phase locked bandwidth of 1.7 MHz. Doppler frequency shift between the signal light and the local laser can be tracked, line width of the laser is compensated and the phase is locked quickly with a final residual phase error of 5.1°.