Objective：To observe the change of drug resistance of QBC939 cells after treatment with verapamil, a competitive inhibitior of P-glycoprotein.
Methods：MMT was used to test the change of verapamil on cisplatin dose curves.
Results：The dose of cisplatin of 50% inhibition was 335.5 μg/L,it decreased to 73.20 μg/L,29.12 μg/L and 17.30 μg/L treated with 10 μg/mL, 20 μg/mL and 40 μg/mL verapamil, respectively.
Conclusions： Verapamil can inhibit cisplatin resistance of QBC939, and the inhibitory effect is related with the concentration of verapamil.