Abstract: The information preservation (IP) method and the direct simulation MonteCarlo (DSMC) method are employed to investigate gas flows throughmicro-pipes with the circular, semi-circular, hexagonal or rectangular crosssections, respectively, as an important issue in thedesign and optimization of MEMS devices. The IP and DSMC results agree wellwith each other, and are compared with the numerical solutions of the BGKmodel equation given by other researchers. For low Mach number casesin micro-pipe flows, the IP method demonstrates the statistically convergentefficiency superior to DSMC. The investigation shows that the cross-sectionshapes of micro-pipes considerately affect their mass flow rates. A relationbetween the mass flow rate and the equivalent Knudsen number for circular,semi-circular, hexagonal and rectangular cross sections is suggested throughfitting the IP and DSMC results.