Electronic structures, exchange interaction mechanism between magnetic ions and Curie temperature of Vanadium-doped nitrides (AlN, GaN, and InN) are studied within KKR-LSDA-CPA. It is found that the ferromagnetic super-exchange interaction mechanism is dominant at low concentrations of Vanadium, but the anti-ferromagnetic super-exchange interaction appears and reduces the stabilization of ferromagnetism at sufficiently high concentrations (x > 0.10), especially for Vanadium-doped AlN and Vanadium-doped GaN. The estimation of the Curie temperature within the mean field approximation shows the Curie temperature of Vanadium-doped nitrides exceeding room temperature with a few constituents of Vanadium.