A sort of arithmetic for wavelet embedded block coding based on low memory and block bit-length search is brought forward in this article. The memory occupancy can be reduced through four measures which adopted in the arithmetic in the process of coding and coding efficiency can be increasingly improved, respectively. The four measures mentioned above are: (1)LLn sub-band separate coding; (2)Establish block bit-length chart, the bit-length is defined by the author; (3)Save the space of memory by employing bit-length chart instead of using lists; (4)Swift search key blocks according to the construction of bit-length chart to overcome repeat scan and increase the coding speed. According to the experimental results, the arithmetic can reduce memory occupancy in the process of coding and increase the coding speed effectively, meanwhile, it can keep the high quality of PSNR. It has great availability in hardware design for wavelet coding.