This study examines the mal-distribution problem in microchannel manifolds. The tubes are of triangular shape with hydraulic diameter of 25 and 50 μm. Ranges of the Reynolds number are from 0.1 to 9. The test results indicate that the mal-distribution decreases with the rise of flow rate. For an inlet flow rate of 0.1 mL/min at the distributor inlet, the maximum difference of the translationsl velocity among manifolds is about 45%. The difference is reduced to 33% if the flow rate is increased to 0.153 mL/min. The maximum translational velocity inside the manifolds is located at the edge of the manifolds and the center portion has the smallest translational velocity. This is because of the spread and turn around water that helps to contribute the increase of flow rate nearby the edge.