Multistage hydrogen Knudsen compressor based on the thermal transpiration effect has very exciting prospect for the hydrogen transmission in the micro devices. Understanding of the hydrogen flow characteristic is the key issue for the designs and applications of the hydrogen energy systems. Firstly, the numerical models of the multistage hydrogen Knudsen compressor are established. The distributions of the rarefaction, velocity and temperature at different stages of the hydrogen flow are calculated and presented. Moreover, the dimensional pressure increases of the hydrogen gas flow are analyzed, and the flow behaviors in the microchannel and the connection channel are discussed. Secondly, the numerical simulation at different connection channel height is implemented, and the hydrogen gas flow characteristics in the connection are analyzed. Especially, the performances of the pressure drop in the connection channel under different channel heights are studied, and the hydrogen gas compression characteristics of different cases are compared and discussed. Also, the effect of the connection channel height on the hydrogen gas pressure increase in the microchannel is investigated. The studies presented in this paper could be greatly beneficial for the hydrogen detection and transmission. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.