Different anode flow fields of air-breathing micro direct methanol fuel cells (μDMFCs) are investigated to improve the cell performances. The single-serpentine flow field can effectively improve the methanol mass transport efficiency and exhibit higher exhaust resultant (CO2) rates than other flow fields such as gird, parallel and double-serpentine. Additionally, the effects of open ratios and channel lengths on the cell performance are evaluated to determine the optimal anode flow field structures. The μDMFCs with different anode flow fields are fabricated using silicon-based micro–electro–mechanical systems (MEMS) technologies and are tested at room temperature. The experimental results show that the single-serpentine flow field exhibits a significantly higher performance than those of other flow fields, demonstrating 16.83mWcm−2 in peak power density and a substantial increase in mass transport coefficients. Moreover, for optimum single-serpentine flow field, it is appropriate for the flow channel dimensions to be in the ratio of 2:3:254 for channel width: ridge width: channel length.