The satellite data transmission system is faced with various threats such as single event upset in semiconductor devices, the transmission noise and so on. The key component of the design and implementation of high-capacity SSR (Solid State Recorder) of the transmission system was introduced, and based on the SSR, a fault tolerance mechanism was proposed to protect management information, data bit stream, satellite-to-ground link and file delivery. The mechanism improved the fault tolerance ability of the management information of SSR, the data in store and the transmission channel with the hamming code, the RS code and the LDPC (Low Density Parity Check Code) encoding. Advanced research of one automatic repeat request method with CFDP (CCSDS File Delivery Protocol) was also proposed based on the SSR of one actual space mission to improve the transmission reliability in file-level. The SSR used 4-pipeline writing and bus expansion techniques to achieve the throughput rate of almost 900Mbps theoretically and the capacity of 256Gb.