Abstract: Adoping the way of test - tube - filter- paper- cultre, comparative observe the ovicidaleffect on Benzimidazole on intestinal nematode eggs ln vltro or vivo. Adoping the ways of saturated brlnefloation and in vitro cultre, observe the effect on Benzimidazole on hookworm in vitro or vivo- The resultsshow that Benzimidazole acted on nematede by inhibition of egg layout sharply. Ovicidal rates to ascaris,trichuris and hookworm in vivo were 97. 8 9%, 100% and l00% respectively on the second day after treatment, and similar result was obtained in vitro. The effectiveness was lower to trichuris, hookworm and ascaris gradully decreased. The process whlch Benzimidazoles act on the lntestinal nematode is slow. Theworms were passed at the third day after drug intervention, and the maximum worm expulsion rate was attained on the fourth day- The observation implied that efficacy is dependent on does regimens and is negative correlated to intensity of infection. In vitro effect of Benzimidazoles on the adult hookworm, it pressented that motiIity was reduced apparently, further more it tended to be " death" within 48 hours.