The invention relates to a slope surface reinforcing testing device. The slope surface reinforcing testing device is characterized by comprising a soil containing device, a rainfall device capable of simulating rainfall situations with different intensities, a pressure bearing device, a water outlet device and an analyzing device for rain washing results. Water outlet devices are distributed at the front end of the soil containing device, and the rainfall device is arranged above the soil containing device; the pressure bearing device is arranged at the adjustable end, close to a water supplying source, of the soil containing device, and the analyzing device is arranged at the back end of the soil containing device. The device can simulate the actual application situation of a soil mass without soil stabilizer and a soil mass with the soil stabilizer in a room, and a reference base is provided for slope surface reinforcing scheme determination through the comparison results of the soil mass without the soil stabilizer and the soil mass with the soil stabilizer.