Abstract: The resistance selection of Tetranychus urticae Koch reared on cotton to meilingmycin and abamectin were carried out. The resistance level,the life vigor and the fecundity were determined after resistance selection for nine consecutive generations.The results showed that the resistance of Meilingmycin-resistance strain was 7.9-fold,the life period of adult,oviposition number of female,hatchability of egg and survival rate of next generation of T.urticae increased by 54.08%,39.93%,6.57%,-15.44% compared with that of the CK respectively after resistance selection of one strain to meilingmycin for nine consecutive generations.When resistance selection of a second strain to abamectin for nine consecutive generations,the resistance of abamectin-resistance strain was 5.8-fold,the life period of adult,the oviposition quantity per ♀,hatchability of egg and survival rate of next generation of the mites were 15.88%,10.87%,5.86%,-9.32% over that in CK respectively.It is clear that the two insecticides have stimulation effects on the development of mites,and have resistance risk.So the two insecticides should be paid attention to timely.