An accurate full-dimensional potential energy surface was developed for the isomerization of CH3NC ⇌ CH3CN. The configuration space relevant to this reaction was exhaustively sampled, accumulating a dataset of 30,974 points, each calculated by CCSD(T)-F12a/AVTZ. Subsequently, the PIP-NN approach was engaged to fit the PES, ensuring rigorous permutation symmetry. The final PES exhibits a total RMSE of 2.54 meV, demonstrating exceptional accuracy in reproducing the properties of the stationary points and the MEP. RPMD calculation was used to obtain precise free energy barrier for the reaction pathway, 1.655 ± 0.004 eV. Additionally, rate coefficients under the high-pressure limit were calculated and were in good agreement with the experimental values. The rate coefficients in the fall-off region were determined using master equation. Again, excellent agreement with experiment was achieved. All these findings suggested that the reaction was in excellent agreement with the predictions of the RRKM theory. QCT simulations were performed on the PIP-NN PES with initial 𝐸vib of 4.336, 5.204 and 6.505 eV to study the dynamical behavior.