本文使用了直接模擬蒙地卡羅法模擬了三種在積體電路中常見的幾何微管，分別是矩形微管、微結構微管與背向式階梯微管，分別利用上述三種幾何微管做了下列幾種探討；首先是利用矩形微管和微結構微管的模擬結果觀察了流場性質與非平衡區之間的關係；接著利用三維五倍的微結構微管與背向式階梯微管觀察位於上下壁面的中心壁面與管角，分析管角效應的影響下與壁面中心的差異度；以及在背向式階梯微管使用了直接模擬蒙地卡羅法以及Gas-BGK法分析了兩個不同稀薄度之流場，觀察兩種模擬方法之間的差異 Microchannel flow has attracted much attention due to the advent of micro-electro-mechanical systems (MEMS), in this paper, the direct simulation Mante Carlo has been applied to compute low-speed Micro-channel Flows, cross-section channel with micro structure, and backward-facing step. In this work, the direct simulation Monte Carlo (DSMC) method is employed to study the gas flows in a two-dimensional backward-facing step for different degrees of rarefaction, and Gas-Kinetic Bhatnagar-Gross-Krook (Gas-BGK) scheme is also performed for solving Navier-Stokes (NS) equations with velocity slip wall boundary condition. The results of microchannel flows show that the non-equilibrium distributed is dependence with the velocity field and Knudsen number. The result showed that the fluid flow to the corner of the wall inside the microchannel was different from the fluid flow to the center of the wall. The influence of fluid flow by the corner of the wall inside the microchannel in 3-D simulation was still different from 2-D simulation.