Abstract: Disk encryption is the core problem of large capacity safety storage.Based on SATA Interface,the paper proposes a design by building a SATA interface bridge.The design has configurable encryption-core which supports SM4 and AES.The paper mainly introduces the implement of SM4.The bridge supports SATA1.0 and SATA2.0 with automatic speed-configuration.FPGA testifies that,disk can be correctly recognized with the bridge.Speed test done by using the software CrystalDiskMark shows that read speed is above 242MB/s with the bridge in the WIN7 system.