Summary: Cancer immunotherapy is an important tumor therapy option for prevention and treatment of tumors and has attracted tremendous interests. However, the therapeutic outcomes are limited by insufficient antigen uptake and presentation by antigen-presenting cells such as dendritic cells (DCs). In this study, mannose-functionalized antigen nanoparticles with endosome escape activity were designed for targeted DCs, accelerated endosomal escape and enhanced MHC-I antigen presentation for cancer immunotherapy. Mannose was selected as DCs targeting ligand to enhance antigen uptake. Model antigen ovalbumin (OVA) was directly conjugated with mannose to obtain DCs targeting antigen, which was then complexed with polyethylenimine (PEI) through electrostatic interaction to form mannose-functionalized antigen nanoparticles (MAN-OVA/PEI NPs). Flow cytometry analysis revealed that the MAN-OVA/PEI NPs greatly increased antigen uptake by DCs compared with OVA/PEI NPs. Confocal laser scanning microscopy further demonstrated that MAN-OVA/PEI NPs enhanced cytosolic antigen release. Moreover, MAN-OVA/PEI NPs significantly promoted cytokine production and DCs maturation ,. More importantly, MAN-OVA/PEI NPs treated DCs exhibited enhanced cross-presentation to B3Z T cell hybridoma ,. This work suggests that mannose-functionalized antigen nanoparticles provide a versatile delivery vehicle for targeted DCs, accelerated endosomal escape and enhanced MHC-I antigen presentation for cancer immunotherapy.