Polymerized ionic liquids (PILs) represent one class of promising candidates for self-healing materials because of the potential diffusion of ion pairs from one aggregation to another. Therefore, dynamics of ionic aggregation plays the crucial role in the self-healing process. However, a win win situation to both self-healing efficiency and mechanical strength is a major challenge for PILs and even all intrinsic healable materials. To resolve this challenge, a series of novel imidazolium-based norbornene PILs with fine-tuned side-chain microstructures were synthesized in the present work. The inserted imidazolium groups divide side chains into two parts: spacer and tail. By tuning the length of these two parts independently, self-healing efficiency of PILs could be significantly improved without sacrificing the mechanical strength. The increase in spacer segments by eight methylenes decreased the glass transition temperature by 70 degrees C and turned the PIL from a strong material into a highly stretchable material. It was very useful to find that tuning the lengths of spacer and tail conversely could achieve comparable mechanical strength. More importantly, our results revealed that long tail segments with 5, 7, or 9 methylenes formed an additional tail region between ionic aggregations, which remarkably reduced the average aggregation distance and consequently accelerates healing kinetics. The understanding on structure-healing interplay provides a convenient and efficient molecular design approach for optimizing mechanical strength and healing efficiency simultaneously.