The oxygen atom coordination inducing the structure reconstruction of the catalytic site is identified and recognized ambiguously, which is related to accurately declare the mechanism in a dynamic catalytic process. Herein, we demonstrated that the reconstructed catalytic sites would lead to a remarkable performance for photocatalytic CO₂ reduction. At the initial 4-cycles testing, the in-situ formation of CoO_x active sites on the Co (CoP) surface performed an increasing transient activity and selectivity toward CO evolution. The formation of reconstructive Co-O bond and the appearance of intermediate specie CO were simultaneously observed by the pre-operando Raman, revealing the dynamic relationship between catalytic site structure and the photocatalytic properties. Moreover, density functional theory calculations showed that the electronic structure of the reconstructive surface sites could modulate the ability of CO₂ adsorption and CO desorption. The reduced barrier energy for the rate-determining step finally improved the activity and selectivity of CO₂ reduction.