Here, we study the relationship between the coordination structure of IrO6 and OER activity in a wide range of oxides with systematic comparisons. The results reveal that distorted IrO6 is more conducive to OER activity. Specifically, for a given material, regulating the transformation of the IrO6 octahedron from D4h compression to D4h elongation causes electrons near the EF level to become more delocalized, which is very beneficial for reducing the energy of the rate determining step. Our findings will guide the design and preparation of more efficient iridium-based OER catalysts.