P>Objective To investigate the effects of BJ46a on invasion and metastasis of melanoma cells. Methods A snake venom metalloproteinase inhibitor BJ46a was produced in baculovirus expression system. Then, recombinant fusion protein was purified by ProBond at the point of maximal expression, SDS-PAGE and Western blotting were used to detect the protein expression. The inhibition activity of matrix metalloproteinasel(MMPs) was detected by purified BJ46a protein. The abilities of tumor cell proliferation and adhension were determined by Alamar blue assay(EM>n/EM>=3).The ability of tumor cell invasion was identified by transwell chamber EM>in vitro/EM>(EM>n/EM>=3). Results The activity of MMPs could be reduced by purified BJ46a protein. The ability of B16 cells treated with recombinant BJ46a to invade the reconstituted basement membrane decreased significantly(EM>P/EM><0.01)，inhibition ratio was 84.8%, but the proliferation and adhension abilities had no change.Conclusion BJ46a might has a strong inhibition effect on the invasion and metatasis potential of B16 cells EM>in vitro/EM>./P>