Abstract: Microscale high efficiency heat exchanger has the character of compact structure,low thermal resistance and high heat transfer coefficient. The density,saturated pressure,surface tension and viscosity of the refrigerant mixed with A and B were calculated and curve fitting of physical properties to temperature with the standard deviation under 1 percent were established. The heat transfer characteristics in a rectangle micro channel with the size of 1.1 mm/1.2 mm at the inlet temperature of -45,20 and 60℃ the external heat flux density of 400 W is studied,the different working condition has the same effective heat exchange heat flux density while the average heat transfer coefficient grows with the inlet temperature.