Aiming at unideal heat transfer effect of traditional plain tubes under high Reynolds number,a method taking water with micro-Cu particles added as working medium to enhance heat transfer in plain tubes was proposed.The multiphase flow heat transfer model of Cu-water microfluid was established.The heat transfer Nu and friction factor f were computed by using Euler-Euler 2-fluid model based on the particle dynamics under different particle diameters of 10μm,50μm,100μm and 500μm,flow velocity of 1m/s,1.5m/s,2m/s and 2.5m/s,and particle volume fraction of 5%,10%,15% and 20%.The results indicated that Nusselt number (Nu) of Cu-water microfluid increases with increase in Reynolds number and particle volume fraction, and decreases with increase in particle diameter; the friction factor f increases with increase in particle volume fraction, and decreases with increase in Reynolds number; the heat transfer comprehensive performance evaluation factor η increases with increase in particle volume fraction, and decreases with increase in particle diameter; the heat transfer comprehensive performance of particles with diameter of 10μm is the best within the studied range of particle diameter, η reaches 1.1 to 2.3.