pyrimidinamine derivatives containing a biphenyl ether moiety were designed and synthesized. Their structures were confirmed by 1H NMR, MS, and elemental analyses. Their insecticidal activities against lepidopteran and hemiptera insects and acaricidalactivities were tested. The results of bioassay demonstrated that 9k showed the best activity (LC50 = 2.08 mg/L) against Tetranychus urticae, which is comparable