Biodegradable polymeric nanoparticles (NPs) have been widely used as the carriers of various kinds of drugs, which are internalized into cells mainly through clathrin-mediated endocytosis and degraded through endo-lysosome pathway.Autophagy is an intracellular process degradation of aggregated proteins, damaged organelles and invaded pathogens.However, the relationship of biodegradable polymeric NPs with autophagy is unclear.Here, we show that various kinds of biodegradable PLGA-based NPs could induce autophagy.The autophagosomes sequester the endo-lysosome escaped NPs into the double membrane vesicles and transport them to lysosomes for degradation.Class Ⅲ PI3K complex controls the regulation of autophagy induced by PLGA-based NPs.Moreover, cancer cells depend on autophagy to resist the chemotherapeutics drugs for survival.Chemotherapeutic drugs-loaded NPs also induce autophagy by both of the NPs and the released chemotherapeutic drugs.Combination with autophagy inhibitors such as 3-methyladenine (3-MA) and chloroquine (CQ) were shown to avoid the capture of NPs and enhance tumor cell killing both in vitro and in vivo.