A three-dimensional numerical model of a methanol steam reforming micro -channel reactor for hydrogen production based on Cu/ZnO/Al-2 O-3 catalyst was established. The effects of different inlet mass flow rate, reaction temperature and steam to carbon ratio (S/C) on the mass change of each component, chemical reaction rate and hydrogen production performance of microchannel reformer were studied. The results show that with the increase of inlet mass flow rate, the mass fraction of CH 3 OH at the outlet of reforming channel increases gradually, and the methanol conversion rate decreases gradually. The mass fraction of CO at the outlet of reforming channel decreases gradually, and the CO selectivity decreases gradually. With the increase of reaction temperature, the mass fraction of CH 3 OH at the outlet of reforming channel decreases gradually, and the methanol conversion rate increases. The mass fraction of CO at the outlet of reforming channel increases rapidly, and the CO selectivity increases rapidly. With the increase of S/C, the methanol conversion rate increased and the CO selectivity decreased. In this study, the influence of reaction conditions on methanol reformer was obtained, and the reasons behind it were clarified, which provided more valuable insights for the operating conditions of hydrogen production from MSR.