Abstract: Experimental results are reported for the flow boiling heat transfer characteristics of nonazeotropic refrigerant mixture of R32 and R134a(25%/75%) in a microchannel with d=0.86 mm.The research results show that when the mass quality is greater than 0.1, the mass quality and mass flux have almost no effects on the heat transfer coefficients of flow boiling.Heat transfer coefficients of the flow boiling in the microchannel are dependent mainly on heat flux.Nucleation is dominant in the heat transfer process for most situations.The flow boiling heat transfer coefficients in microchannel are 30%—200% higher than those in normal tubes.Experimental correlation is presented with deviation of no more than 25%.