Monodispersed water-in-oil emulsions were prepared successfully using polymer microchannel (PMC) with hydrophobic property, low cost and high anti-alkalinity fabricated by molding injection method. In order to enhance the efficiency of PMC emulsification, it is important to know the critical flow velocity of the dispersed phase, and the critical pressure at which the dispersed phase outflow occurs. In this study, we investigated the effect of the continuous phase flow velocity on the average droplet diameter, coefficient of variation, and the critical pressure during the PMC emulsification process. Furthermore, aiming the optimization of PMC pattern for efficient production of emulsion, various PMC plates with different structures were fabricated, and were used for emulsification. The effects of various parameters on droplet formation characteristics were investigated. The results showed that the continuous phase flow velocity did not affect the average droplet diameter and coefficient of variation, but affected the critical pressure. The critical flow velocity increased slightly, when PMC plates with different structures were used. In particular, the average droplet diameter range became wider, coefficient of variation decreased, and the critical flow velocity increased significantly with the increase of PMC length, which showed higher productivity of the emulsion.