Abstract: In order to obtain the optimal pre- cooking conditions and parameters of Apostichopus japonicus,its quality changes were studied in the process of boiling with distilled water( I) or saline solution with different concentration( 1%,3%,6%)( Ⅱ,Ⅲ,Ⅳ) and steaming with no water( Ⅴ) or water( Ⅵ).The results were as follows:mcrobial residues and crude protease activity declined with time. The sequence of the ability of lowering bacteria and protease activity was( Ⅰ,Ⅱ,Ⅲ and Ⅳ),Ⅴ,Ⅵ,but there were no significant differences among Ⅰ,Ⅱ,Ⅲ andⅣ( p > 0.05). The time for decreasing one order of magnitude of bacterial count by three treatments needed 12 min,15 min and 18 min respectively.The time for the change of enzyme activity began to slow down was 9 min,12 min and 15 min respectively. The sequence of the final losses of crude protein was( Ⅲ,Ⅳ),( Ⅰ,Ⅱ),Ⅴ,Ⅵ,but there were significant difference between( Ⅲ,Ⅳ) and( Ⅰ,Ⅱ)( p < 0.05).The sequence of the final losses of crude polysaccharide was( Ⅰ,Ⅱ),( Ⅲ,Ⅳ),Ⅴ,Ⅵ. On texture changes,the boiling treatments were slower than the steamed ways,especially the texture changes of Ⅵ was slowest. Ⅰ and Ⅴ were appropriate pre- cooking ways and the optimum time of thermal processing were 12 min and 15 min respectively