The effect of the fourth-nearest pair potentials on the precipitation mechanism of Ni75Al5V20 alloy is studied using a microscopic phase-field kinetic equation. Our simulations demonstrate that both DO22 phase and L12 phase have a mixed precipitation mechanism of non-classical nucleation growth and spinodal decomposition without changing the fourth-nearest pair potentials. When the absolute value of the fourth-nearest pair potential between Ni and Al (namely V4Ni-Al, negative) increases, the precipitation mechanism of L12 phase becomes spinodal decomposition. And when the fourth-nearest pair potential between Ni and V (namely V4Ni-V) increases, the precipitation mechanism of DO22 phase is spinodal decomposition, the L12 phase is non-classical nucleation and the Al concentration in L12 phase gains. When the absolute value of the negative V4Al-V increases, the mechanism is similar to the increase of V4Ni-V; when the positive V4Al-V increases, the mechanism is similar to the decrease of V4Ni-V