A strain of actinomyces (named as 218 powder) was seperated from snail-inhabitated soil and was identified as streptomyces diatatochromogenes. The corrected mortality rate of snails exposed to 0. 1 % concentration of the shaking fermentation liquid was 96% -100%, and that of the snails exposed to 10 mg/L of 218 powder as industrial product for 48 h in the laboratory was 98.0%. The hatching rate of snail eggs exposed to 100 mg/L of the bacterial powder for 48 h was 9. 0%. The corrected mortality of snails exposed to 75 mg/L of bacterial powder for 48 h in the field was 96. 9%, and this biological molluscicide did not damage plants but had some slow acting toxicity to fish.