Abstract: Charge-reversal nanocarrier was constructed to enhance lysosomal escape and improve an-titumor effect. We synthesized the cholesterol-polyethyleneimine-hexahydrophthalic anhydride (Chol-PEI-HHPA) polymer and characterized by ¹H NMR. The charge-reversal liposomes (Lipo-HHPA) were synthesized and the hematoporphyrin monomethyl ether (HMME) was loaded. pH-triggered charge conversion was determined at different pH values. The lysosomal escape and cytotoxicity of the Lipo-HHPA were evaluated in MCF-7 cells. The Lipo-HHPA was uniform with an average particle size of 102 nm. Upon the irradiation of ultrasound, burst release of HMME could be observed. The zeta potential of Lipo-HHPA changed sharply from negative (-23.5 mV) to positive (+21.2 mV) over the pH range of 7.4-4.5. In the cellular uptake experiment, the lysosomal escape of Lipo-HHPA was observed. HMME loaded Lipo-HHPA displayed obviously enhanced cytotoxicity towards MCF-7 cells. These results indicate that the charge-reversal liposomes hold a great potential in improving the cytotoxicity and antitumor effect.