In order to study the influence of cross-sectional area of micro Direct methanol fuel cell on bubble flow, the VOF method in FLUENT was used to study the serpentine channel. The range of depth was 0.2 mm, 0.4 mm, 0.6 mm The width range is 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm. Assume that the flow pattern is Laminar, all Incompressible flow, and ignore gravity. The results show that the pressure drop at the inlet and outlet of the snake-shaped runner increases with the decrease of the runner depth When the width of the shoulder is 0.75 ~ 1 times of the width of the runner, the discharge time of the bubble section is shorter and the pressure drop of the inlet and outlet is larger.