The　development　of　probes　for　early　monitoring　tumor　therapy　response　may　greatly　benefit　the　promotion　of　photodynamic　therapy　(PDT)　efficacy.　Singlet　oxygen　(O-1(2))　generation　is　a　typical　indicator　for　evaluating　PDT　efficacy　in　cancer.　However,　most　existing　probes　cannot　quantitatively　detect　O-1(2)　in　vivo　due　to　the　high　reactivity　and　transient　state,　and　thus　have　a　poor　correlation　with　PDT　response.　Herein,　a　O-1(2)-responsive　theranostic　platform　comprising　thiophene-based　small　molecule　(2SeFT-PEG)　and　photosensitizer　Chlorin　e6　(Ce6)　micelles　for　real-time　monitoring　PDT　efficacy　is　developed.　After　laser　irradiation,　the　Ce6-produced　O-1(2)　could　simultaneously　kill　cancer　and　trigger　2SeFT-PEG　to　produce　increased　chemiluminescence　(CL)　and　decreased　fluorescence　(FL)　signals　variation　at　1050　nm　in　the　second　near-infrared　(NIR-II,　950-1700　nm)　window.　Significantly,　the　ratiometric　NIR-II　CL/FL　imaging　at　1050　nm　could　effectively　quantify　and　monitor　the　concentration　of　O-1(2)　and　O-2　consumption　or　recovery,　so　as　to　evaluate　the　therapeutic　efficacy　of　PDT　in　vivo.　Hence,　this　O-1(2)　activated　NIR-II　CL/FL　probe　provides　an　efficient　ratiometric　optical　imaging　platform　for　real-time　evaluating　PDT　effect　and　precisely　guiding　the　PDT　process　in　vivo.