Cathode’s primary particle structure plays a key role in the performance of lithium ion batteries, which can be controlled by the precursor synthesis. Regretfully, the relevance between primary particle structure and cathode performance is not explicitly elucidated, that is, what is the discrepancy of cathode’s primary particle size on the structural degradation? In order to elaborate the structure-activity relationship between them, we have systematically investigated the regulation of primary particle size through an in-depth analysis of the precursor growth mechanism, ammonia-stirring coupling and hydrodynamics optimization. Structural and electrochemical characterizations of LiNi0.92Co0.04Mn0.04O2 with different primary sizes (336, 447, 565 and 675 nm) and a rounded analysis of structural degradation after cycling provide insight into the correlation between precursor fine structure and cathode performance, i.e. larger cathode’s primary particle size can effectively inhibit CEI film formation, structure decay, the intragranular/intergranular cracks formation owing to the alleviation of localized stress.