In this paper, the authors mainly aims at solving the problems of sampled data synchronization in digital substation based on Field Programmable Gate Array (FPGA). Compared with traditional substations, the design achieves data synchronization without connecting an external clock. Synchronization algorithm is based on Newton interpolation algorithm. The system consists of multi-channel data sampling module, synchronization module, Ethernet module etc. The design realizes the concept of modular design with FPGA processor, ensuring that each sub-module gets parallel execution.