Chemical reaction pathways and product state correlations of gas-phase ion-molecule reactions are governed by the involved potential energy surfaces (PESs). Here, we report the photodissociation dynamics of charge-transfer complex [Ar-N2]+, which is the intermediate of the model system of the Ar+ + N2 → Ar + N2+ reaction. High-resolution recoiling velocity images of photofragmented N2 and N2+ from different dissociation channels exhibit a vibrational state-specific correlation, revealing the nonadiabatic charge-transfer mechanisms upon the photodissociation of [Ar-N2]+. The state-resolved product branching ratios have yielded an accurate determination of the resonant charge-transfer probabilities. This work provides a powerful approach to elucidating the detailed dynamics of chemical events of charge-transfer complex [Ar-N2]+ and to probing the state-to-state charge-transfer PESs.