The synchronization of digital phased array radar in radar array design is a key problem. This radar array is a set of ADC array, DAC array and PROCESS array. The sampling rate and array size is the decisive synchronization difficulty index. The synchronization target of big size array is discussed, the timing synchronization conditions difficulties including the skew and the jitter of reference clock and work clock and synchronization clock. Multiple innovative approaches are adopted，include distributed frequency synthesize, synchronization distribution network，real-time monitoring and delay-adjust. Thus accurate synchronization is achieved