The GEM resistant PANC1 cell line （PANC1/GEM） was established by low concentration sequential increasing method， and the cells were divided into GEM resistant group （PANC1/GEM group）， CQ group and GEM resistant+CQ group （PANC1/GEM+CQ group）， and the PANC1 cells were used as control group at the same time. CCK-8 method was used to verify whether the cell line was successfully established.The number of autophagy bodies was observed by transmission electron microscope， and the expression levels of autophagy marker proteins cytoplas microtubule-associated protein 1 light chain 3 （LC3-Ⅰ），membrane microtubule-associated protein 1 light chain 3 （LC3-Ⅱ） and P62 proteins were detected by Western blotting method； JC-1 method， DCFH-DA， Annexin Ⅴ-FITC/PI double staining and flow cytometry were used to detect the mitochondrial membrane potential，the reactive oxygen species （ROS） levels and the apoptotic rates of the cells in various groups. The expression levels of apoptosis related proteins B cell lymphoma-2（Bcl-2）， Bcl-2 associated X protein（Bax） and Cleaved caspase-3 proteins in the cells in various groups were detected by Western blotting method.

The PANC1/GEM cell line was successfully established， and the IC₅₀ value of GEM to the PANC1/GEM cells was significantly increased compared with PANC1 cells（P<0.01）. Compared with control group， the number of autophagy bodies and the LC3-Ⅱ/LC3-Ⅰ ratios in PANC1/GEM group， CQ group and PANC1/GEM+CQ group were significantly increased （P<0.05）， and the levels of P62 protein in PANC1/GEM group and PANC1/GEM+CQ group were significantly decreased （P < 0.05）， and the expression level of P62 protein in CQ group was significantly increased（P<0.05）. Compared with PANC1/GEM group， the LC3-Ⅱ/LC3-Ⅰ ratio in PANC1/GEM+CQ group was significantly decreased（P<0.05）， and the expression level of P62 protein was significantly increased （P<0.05）.Compared with control group， the mitochondrial membrane potentials of the cells in PANC1/GEM group and PANC1/GEM+CQ group， the ROS levels and the apoptotic rates were significantly decreased （P<0.05），and the mitochondrial membrane potential，the ROS levels and the apoptotic rate in CQ group were significantly increased （P<0.05）；compared with PANC1/GEM group，the mitochondrial membrane potential，the ROS level and the apoptotic rate in PANC1/GEM+CQ group were significantly increased（P<0.05）.Compared with control group， the expression levels of Bcl-2 protein in PANC1/GEM and PANC1/GEM+CQ groups were increased （P<0.05）， while the expression levels of Bax and Cleaved caspase-3 proteins were significantly decreased （P<0.05）；the expression level of Bcl-2 protein in CQ group was significantly decreased （P<0.05），and the expression levels of Bax and Cleaved caspase-3 proteins were significantly increased （P<0.05）. Compared with PANC1/GEM group， the expression level of Bcl-2 protein in PANC1/GEM+CQ group was significantly decreased （P<0.05）， while the expression levels of Bax and Cleaved caspase-3 proteins were significantly increased （P<0.05）.

CQ can significantly promote the sensitivity of drug-resistant PC cells to GEM， the mechanism of which may be related to the inhibition of autophagy of pancreatic cancer cells， the reduction of mitochondrial membrane potential， the promotion of ROS production in the cells， and the up-regulation of GEM-induced apoptosis.