Abstract:  For the real-time imaging sonar, the imaging data require to be compressed to transmit to the littoral combat ship (LCS) in some cases such as in the wireless communication between a LCS and a remote multi-mission vehicle (RMMV). In this paper, a discrete cosine transform (DCT) and subsection quantization based imaging data compression method was proposed, which could apply to the real-time sonar imaging row data. The steps of the method were as follows. Firstly the row data were transformed by DCT. Secondly the DCT sequence was truncated for its strong “energy compaction” property. Finally the truncated data were divided into several subsections, each of which was quantized separately. In the display end, which usually located in a LCS, after an adverse processing, the decompressed imaging raw data would display on the screen in real time. The method was applied to the lake trial sonar data, indicating this effective solution.