Objective To study proteomic differential expressions of mouse osteoblasts stimulated by mechanical strain. Methods Mouse osteoblasts were randomly divided into two groups:experimental group were subjected to mechanical strain of 0.5 Hz, 2000 με for 6 hours by using four-point-bend loading system;control group did not undergo any stress. Proteins extracted from cells were separated by two-dimensional electrophoresis ( 2-DE), and the differentially expressed protein spots were analysed. Results A total of( 533±14)and( 512±11) protein spots were resolved by 2-DE of experimental and control groups extractions , respectively.Nine protein points displayed significant changes in strain treated osteoblasts, 7 increased in expression and 2 decreased. Conclusions The osteoblasts can express differential proteins stimulated by mechanical strains and these proteins may play an important role in molecular mechanism of osteoblasts under mechanical strain loading.