A Double Data Rate(DDR) Synchronous Dynamic Random Access Memory(SDRAM) combined with Quad Data Rate(QDR) Static Random Access Memory(SRAM) storage system is proposed to overcome the problem of huge amount of SAR imaging echo data. An in-place transposed storage method is designed for the system to improve the memory resource utilization. This method compares the length of the range and the azimuth of radar echo data firstly. It reserves some free space of the memory to improve the flexibility of the logical mapping of the read address and the write address of memory. The free space is the same as the storage space occupied by a single row or column of longer data in the range direction and the azimuth direction. It effectively realizes the on-chip transposition operation of a large amount of data, and saves the utilization amount of DDR. And the sub-block matrix address mapping method and cross-BANK address mapping method are applied to the in-place transposition, which effectively improves the access to the SAR echo data transposition. The experimental results show that the data storage system reduces the amount of DDR memory by half while meeting the real-time imaging requirement, improves the resource utilization of DDR, and cuts the cost. At present, it has been successfully applied to SAR imaging processing in multiple modes.