In order to pick out the efficent insecticide to Tetranychus truncatus Ehara, the laboratory drug-effect test was done on its experimental population by spraying underleaf on culture plates, sixteen types of insecticide were choosed, the result revealed that:.The effects of Methidathion and Dicofol were best, they showed 100% effect three days after spraying;Comite, Nonmite and Mitac showed 99% or higher effect seven days after spraying. To prevent Tetranychus truncatus Ehara, it is better to choose Methidathion and Dicofol, Comite, Nonmite and Mitac can be used according to different situations;The best way to increase the insecticidal effect is to spray underleaf.