Based on the experimental platform of a visualized constant volume combustion bomb, a computational model was established by using CONVERGE software. Numerical simulation was conducted to investigate the jet ignition of methanol mixture in the pre-chamber and the combustion process in the main chamber. The effects of pre-chamber structures on methanol combustion performance were analyzed, incluidng three structures of without baffle, flat baffle and conical baffle. The results show that the combustion process in the combustion chamber consists of four stages such as the flame propagation stage in the pre-chamber, the jet development stage, the main combustion chamber combustion stage, and the late combustion stage. The pre-chamber jet is a continuous process consisting of cold jet, hot jet and reverse jet. When the equivalence ratio of main combustion chamber is 0.5, the conical baffle pre-chamber structure shows the optimal combustion performance. Compared with the pre-chamber without baffle, the combustion duration for flat baffle and conical baffle configuration shortens by 3.5% and 10.5% respectively. The lean-burn limit of methanol remains 0.4 for all the three pre-chamber structures. When the equivalence ratio of main combustion chamber is 0.4, the pre-chamber without baffle is most favorable for methanol combustion, with a peak heat release rate of 3 329 J/ms.