Carboxymethyl chitosan (CMCS), one of the most important water soluble chitosan derivatives, has great potentials in biomedical applications due to its excellent water solubility, biodegradability, biocompatibility, and non-toxicity. In the present study, the anti-tumor metastasis effect of CMCS on hepatic tumors was evaluated using human hepatic cancer cell BEL-7402 and mouse hepatoma 22 cells. The results suggested that CMCS could significantly inhibit tumor cell migration in vitro, and reduce the expression of matrix metalloproteinase-9 in BEL-7402 cells in a dose-dependent manner (P<0.05). Furthermore, CMCS significantly inhibited the lung metastasis of hepatoma-22 in Kunming mice (P<0.05). Significant improvement of the lung injury caused by the metastasis of H22 was also observed. The results suggested that the inhibitory effect of CMCS could be attributed in part to the decreased levels of vascular endothelial growth factor and E-selectin in CMCS treated mice.