AIM:　To　study　the　anti-viral　effect　of　Ren　Xian　Cao　(RXC),　extracted　from　compound　agent　Qiedu　Zengning　capsule　ZL-1,　on　the　replication　of　hepatitis　B　virus　(HBV).　METHODS:　HepG2.2.15　cells　were　co-cultured　with　different　concentrations　of　RXC,　and　enzyme-linked　immunosorbent　assay　(ELISA)　was　used　to　examine　the　secretion　of　HBsAg　and　HBsAg.　Duck　models　of　HBV　infection　was　established　by　intravenous　injection　of　duck　HBV,　and　then　treated　with　different　doses　of　RXC.　The　changes　of　duck　HBV　DNA　were　observed.　RESULTS:　After　RXC　addition　for　8　days,　the　half　toxic　concentration　(TC50)　of　RXC　was　1126.01　mg/L,　and　the　half　inhibitory　concentration　(IC50)　on　the　secretion　of　HBsAg　and　HBeAg　was　17.52　and　754.26　mg/L,　respectively.　The　value　of　therapeutic　index　(TC50/IC50)　for　HBsAg　and　HBeAg　was　64.27　and　1.49,　respectively.　RXC　at　a　dose　of　0.8　g/kg　significantly　lowered　the　level　of　serum　duck　HBV　DNA　at　the　5th,　10th　day　of　treatment　and　3　days　after　the　end　of　treatment　as　compared　with　normal　saline　did　(absorbency:　0.660　±　0.07,　0.632　±　0.03,　0.663　±　0.05　vs　0.872　±　0.08,　P　<　0.05).　CONCLUSION:　RXC　has　inhibitory　effect　on　the　replication　of　HBV.