Liposomal delivery system that concurrent delivery of multiple drugs can improve efficacy of cancer treatments, yet remain challenging because of differential properties, fairly low loading thresholds of many drugs, and drug burst release. Here, we report a ratiometrically designed liposomal nanoplatform with synergistic efficacy, utilizing remote loading to co-encapsulate ROS-sensitive paclitaxel prodrug (PSN) and doxorubicin (DOX). This novel dual-delivery liposomes possess high two-drug encapsulation efficacy and colloidal stability, resulting in synergistic cytotoxicity, extended blood circulation, favorable biodistribution, always maintain the ratiometrically synergistic drug ratio in vivo, and potent synergistic anticancer activity. Such a combination of PSN and DOX with synergistic effects encapsulated in a safe and effective dual-delivery liposomal nanomedicine may hold promise for the further clinical translation and provides a new strategy for high-efficient combination chemotherapy.