Abstract: Effects of killing snails of the Pachysandra terminalis powder and the extraction(PT-Ⅰ) were studied by the open immersion method,and their toxicities to fish were studied too.The snail mortality was 93.4% for 72 h immersion,and 100.0% after 120 h immersion,with 17.5 mg/L P.terminalis powder.LC₅₀ of the P.terminalis powder to the snail for 24,72,120 and 168 h were 42.28,7.20,4.20,3.17 mg/L.The fish mortality was zero at the concentration of 75.0 mg/L for 168 h.After immersion for 1,2,18,42 h with 35.0,17.5,8.75 and 4.38 mg/L P.terminalis,the upward-climbing inhibition rate of the snail were 100.0%.The snail mortality were 36.7%,73.3%,96.7%,96.7% and 100.0% when they were immersed in the solution of 1.40 mg/L PT-Ⅰ for 24,48,72,96 and 120 h,respectively.The results suggested that P.terminalis have good effect of killing snail and high climbing-upward inhibition rate and it has lower toxicity to fish.Thus it could be a potential plant molluscicides.