Objective:　To　investigate　the　suppressing　effect　of　cadmium　chloride　on　proliferation　of　hepatocarcinoma,　and　to　discuss　the　mechanism　for　the　difference　of　cadmium　chloride　between　normal　and　tumor　tissue.　Methods:　Hepatocarcinoma　cell　lines　HepG-2　and　SMMC-7721　were　treated　with　5,　10,　25　and　50　μmol·L-1　cadmium　chloride　for　6　h,　MTT　essay　was　used　to　measure　the　inhibition　of　proliferation　of　HepG-2　and　SMMC-7721　cells;　Instantaneously,　HepG-2　and　SMMC-7721　cells　were　treated　with　25　μmol·L-1　cadmium　chloride　for　different　time,　the　inhibition　of　proliferation　was　also　measured.　Athymic　mice　were　used　to　establish　the　human　hepatocarcinoma　animal　models,　the　survival　day　and　tumor　volume　8　weeks　after　drug　administration　were　detected;　the　metallothionein　(MT)　levels　in　normal　and　tumor　tissues　were　determined　by　immunohistochemimal　staining.　Results:　Compared　with　control　group,　5,　10,　25　and　50　μmol·L-1　cadmium　chloride　inhibited　the　proliferation　of　hepatocarcinoma　cell　lines　(P　<　0.05),　the　inhibitory　rate　increased　with　the　dose　of　drug　and　action　time.　Compared　with　control,　the　tumor　volumes　in　model　mice　were　significantly　decreased　in　0.25,　1.00　and　4.00　mg·kg　-1　cadmium　chloride　and　ZnCl2+CdCl2　groups　(P　<　0.05)　and　the　survival　day　increased　(P　<　0.05).　The　tumor　volume　in　ZnCl2　+　CdCl2　group　had　no　difference　with　1　mg·kg-1　cadmium　chloride　group,　however,　the　survival　day　was　longer　(P　<　0.05).　The　result　of　immunohistochemical　staining　showed　the　MT　level　in　hepatocarcinoma　tissue　was　significantly　lower　than　that　in　normal　liver　tissue,　the　MT　level　was　increased　significantly　in　normal　liver　tissue　pretreated　with　ZnCl2,　otherwise　it　was　no　change　in　hepatocarcinoma　tissue.　Conclusion:　Cadmium　chloride　has　anti-tumor　effect　on　hepatocarcinoma.　Pretreatment　with　ZnCl2　could　increase　the　MT　level　in　normal　liver　tissue;　the　MT　level　in　tumor　tissue　is　lower　and　could　not　be　induced　by　zinc.