An aliphatic SNS manganese pincer complex is computationally predicted as a promising catalyst for the hydrogenation of acetophenone to 1-phenylethanol. Density functional theory (DFT) calculations indicate that the total free energy barrier is 26.6 kcal/mol. Detailed reaction dynamics processes of two key steps, methanol assisted H-2 cleavage and hydrogenation of acetophenone, are analyzed by using ab initio molecular dynamics (AIMD) simulations. Our AIMD simulation results confirmed the proposed catalytic mechanism based on DFT calculations and revealed that the H-2 cleavage happens between 0.3 and 0.7 ps, while the hydride transfer from Mn to carbon happens at around 0.1 ps.