CL imaging, especially NIR-II CL imaging, can conquer the limitation of excitation light to ensure deep tissue penetration, high SBR, and high sensitivity. However, there is still big space for improving the QY of the CL imaging systems. This problem could be solved by utilizing NIR-II dyes with high QYs as energy acceptors. Here we designed an efficient NIR-II CL imaging system, which was realized by successive CL resonance energy transfer (CRET) and Förster resonance energy transfer (FRET) processes (Figure ). The TPE-BBT chemiluminescent nanoparticles (CLNPs) were dispersed by F127 in water, co-encapsulated with bis[ showed that TPE-BBT CLNPs were successfully prepared with an average diameter of 30 nm (Figure ). BTD540 and TPE-BBT in nanoparticles showed large Stokes shifts, and the emission of BTD540 presented perfect spectral overlap with the absorption of TPE-BBT (Figure ). These results ensured an efficient FRET process between BTD540 and TPE-BBT. To verify the FRET process, we measured the PL spectrum of the mixture of BTD540 and TPE-BBT in nanoparticles in water (Figure ). The process in this CL imaging system (Figure ). To study the importance of the QY of NIR-II AIEgens in building an efficient NIR-II CL imaging system, TPA-BBT CLNPs were also prepared through a similar method to TPE-BBT CLNPs, except that TPA-BBT was used as the NIR-II energy acceptor. The spectral studies also indicated an efficient FRET process between BTD540 and TPA-BBT (Figure ). Then, the response to H 2 O 2 of these two prepared CLNPs were tested, respectively. Both CLNPs were effectively lightened at room temperature upon the addition of H 2 O 2 , and the CL intensity increased at higher concentrations of H 2 O 2 (Figure ). ). The intensity profiles along the arthrosis position (Line 1 and Line 2 in Figure ) showed that TPE-BBT CLNPs had a stronger CL intensity (Figure ), and provided more specific imaging for arthrosis inflammation. We then set the arthrosis inflammation as the region of interest (ROI) and recorded the CL signals for a longer time (Figures and). The SBRs in the ROI at different time points were also calculated and recorded in