Abstract: The abamectin represents an important resource for pest control, because of its novel mode of action. Thus, the question is not whether resistance to abamectin will occur but is when it will occur. To address this problem, we had selected a susceptible strain of two-spotted spider mite Tetranychus urticae Koch under pressure of killing about 60% population with abamectin. The population was tested every five generations by slide-dip method and LC-P line was received. The result indicated that the development of resistance to abamectin was quickly, after 20 cycles exposure, the resistance ratios of selected population was 8.09. Moreover, there had been homozygotes in the population.