Herein, we report a turn-on strategy for selectively killing the tumor cell via combining the singlet-oxygen quenching MnO and tumor cell-targeting aptamer. The photosensitizers were in the quenching state when loaded in the mesoporous MnO (mMnO) nanoparticles and sealed by the aptamer on the particle surface. The aptamer can selectively recognize the specific membrane protein on the tumor cell and release the photosensitizers, activating the photosensitizer and killing the tumor cells. The specific binding-induced "off-on" switching of singlet oxygen generation reduced the damage to the nearby healthy cells to a large extent. The high loading ability for photosensitizer and the GSH consumption property of mMnO endow the system with high local concentration of singlet-oxygen for killing the target tumor cell. The high selectivity and efficiency of the constructed singlet oxygen regulating system will pave a new way for utilizing PDT in cancer precise treatment.