The utility model provides a rainfall infiltration law test system based on aqueous vapor two -phase flow, it includes cylinder body and main control device, cylinder body bottom is equipped with the metalling, is equipped with the drain pipe in the cylinder body bottom, is equipped with the control valve on the drain pipe, is equipped with on the metalling and builds the earth material layer, main control device is connected with the data acquisition device, and the data acquisition device passes through data line and humidity transducer, pressure sensor, and drain pipe, rainfall spray tube set up in building earth material layer upper portion and being connected with water pump, dust -collecting bucket, and weighing sensor sets up in the dust -collecting bucket bottom and is connected with the data acquisition device. Different raininess, different multiple border and the initial condition such as gas condition, different runoff, different soil samples of sealing can not only be simulated to this device, can not have atmospheric pressure, the water content of disturbance, the automatic real -time supervision soil body, speed, the temperature etc. Of infiltrating simultaneously and change indexs, and are especially adapted in the research to soil body unsaturation area moisture migration law.