In this paper，we study the development of novel multiscale parallel micro-channel contactor for monodisperse waterin-oil emulsification． Oils with different physical properties ( pure oil，0. 3% span83，0. 4% span83) and water are chosen as a continuous phase and a dispersed phase respectively． By using novel multiscale contactor ( sixteen parallel Ytype channels) which offers an equal distribution of flow rate with low energy cost ( less than 35J/kg) ，we have studied and discussed the influence of two-phase flow physical properties ( such as flowrate ratio，surface intension and capillary number) on the emulsion polydispersity experimentally and numerically． Capillary number ( Ca) plays an important role in emulsification progress，and when Ca is less than 0. 01， the mono-disperse emulsion is better． As the surface tension of the two-phase flow increases， the emulsion poly-dispersity is lower and the density of the emulsion reduces． When the surface tension rises to 27. 6mN/m， the polydispersity ( Pw) ranging from 3. 0% to 5. 8% is half of the Pw of water -0. 3% span83 emulsions．