Conjugated polyelectrolytes prepared from carbon-carbon coupling polymerization have difficulties in controlling the precision molecular weight (M-n), so that the effect of M-n on their performance remains vague. Herein, we develop a strategy to prepare well-defined polyelectrolytes with adjustable M-n through a combination of controllable polymerization and aggregation-induced emission (AIE) technique. The resultant tetraphenylethylene-labeled polycarbonates show tunable M-n in the range of 2300-9500 g mol(-1), which is further quantitatively converted to polyelectrolytes via thiol-ene click chemistry. The AIE-active polyelectrolytes are used for Zn2+ detection to decipher structure-functionality relationships. Fluorescence variation indicates that Zn(2+ )detection is tightly associated with M-n. For M-n < 5600 g mol(-1), the shrinkage of the nanoparticle is caused by the diffusion of Zn2+ into the loose space between the COO- groups in a single nanoparticle. For M-n > 7600 g mol(-1) , the possible entanglement and wrapping of long chains hinder the diffusion of Zn2+, triggering the coordination of Zn2+ between different nanoparticles. This work may provide insights into comparing the self-assembly behavior of materials with different architectures.