The combination of functional polymers and hydrophobic AIE dyes to prepare luminescent organic nanoparticles (LONs) with strong fluorescence, great water dispersibility and desirable biocompatibility have received numerous attentions for their potential applications in cell imaging and theranostics. Although great effort has been devoted to preparing AIE dye based LONs through both covalent and 10 noncovalent strategies, the fabrication of cross-linked AIE dye based LONs with stimulus responsive behavior has not been reported previously. In this work, the AIE dye based LONs were constructed via cross-linking aldehyde-containing polymers and AIE dye (2,2'-diaminotetraphenyl ethylene) with two amino groups through formation of Schiff base, which is a well known dynamic bond with pH responsiveness. After successful incorporation of the hydrophobic AIE dye into the copolymers, cross-15 linked core-shell lunminescent nanoparticles can be formed. The obtained AIE dye based LONs exhibited strong fluorescence and high water dispersiblity because the AIE dye was aggregated in the core and the hydrophilic polymers were covered on the shell. Biological evaluation results demonstrated that the AIE dye based LONs exhibited excllent biocompatibility and biological imaging properties. More importantly, these AIE dye based LONs exhibited desirable pH responsiveness, implied that these polymeric LONs are 20 potentially utilized for pH sensor and controlled drug delivery. Combination of the dynamic crosslinking and pH responsiveness, the obtained AIE dye based LONs should be of great significance for biomedical application.