Microchannel reactors are currently one of the most promising technologies in the field of portable hydrogen production. In order to improve the effectiveness of methane steam reforming for hydrogen production in microreactors, three geometrical models of microreactors with different structures are designed, namely, pipe model, FCC model, and Tri-g ISB model. Numerical simulations of three different microreactors are carried out using Ansys Fluent fluid simulation software in conjunction with the CHEMKIN reaction mechanism file of hydrogen production from methane steam reforming. By studying the gas composition changes at the outlet of microreactors under different conditions, it can be seen that the smaller the inlet velocity is, the higher the CH4 conversion and H2 volume fraction are; When S/C>3, the higher the conversion rate of CH4 increases to more than 80%, and the content of H2 increases to more than 73vol%; The higher the temperature is, the more stable the CH4 conversion can be at 99.9%, almost completely transformed, and the H2 content increases to more than 77vol%. However, the higher the temperature is, the lower the H2 output will be, and the higher the CO content will be. By calculating the time required for the microreactor to reach stability under different conditions, it can be seen that with the increase of inlet velocity and S/C, the stability time gradually decreases and tends to be stable, and with the increase of wall temperature, the stability time first decreases and then increases. By comparing the three kinds of microreactors, it can be seen that the complex structure can enhance the performance of the micro reactor, but will increase the time required for the microreactor to reach stability. In terms of microreactor performance, FCC model is the best, and pipe model is the worst; In terms of stability time, the stability time increases with the increase of structural complexity. The pipe model is the shortest and the Tri-g ISB model is the longest; The complexity of the microreactor structure is different, and the performance improvement is also different. The overly complex structure will inhibit the performance of the microreactor.