With the development of space technology, the data of space remote sensing image are expanded greatly. To meet the real-time processing need of satellite on-board JPEG2000 image compression system, the optimization and improvement for the compression algorithm, as well as the design of high speed hardware process system are investigated. The Discrete Wavelet Transform(DWT) algorithm based on post-scaling lifting and quantification algorithm of JPEG2000 are analysed. Then, by a new scaling-quantification factor, the two processes of scaling in DWT and quantification are combined into one process to remove the quantification process in JPEG2000. Finally, the fixed-point implementation in the quantification removing method is brought forth. Experimental results indicate that the time for implementation scaling and quantification has been decreased by 50% with the new method,and the real-time processing ability of the satellite on-board JPEG2000 image compression system can be improved greatly.