We modified the traditional Navier-Stokes equation, and used the Fluent software to simulate the microscopic law of flow of Zn-Al alloy melt in the micro-channel. The simulation results show that when the diameter of the channel is 0.5mm， the liquid metal in the micro-channel is in a critical state. Relative thickness of boundary-velocity layer increases with the decrease of diameter of the channel, and micro-channel flow shows obvious convex-front effect, which has not been observed in the macroflow. The convex-front effect weakens when the inlet pressure increases. Between the flow front and upstream region, there exist negative pressure gradient zones, which become more outstanding in finer channels.