[ Background] Rainfall simulator is commonly used in indoor and outdoor soil erosion research and the process of infiltration and rainfall runoff study. However, tall nozzles, small efficient rainfall area, and differences from natural rainfall constraint some rainfall simulators widely used. Based on all above, we developed a Rocker Arm Top Spray rainfall simulator which is supposed to be used widely. [Methods] The Rocker Arm Top Spray rainfall simulator we developed was composed of three rainfall nozzles (number1, 2, and 5, aperture 9 mm), two middle rainfall nozzles (number 3 and 4, aperture 13 mm), Axle tube, “cross type冶rocker arm, Axle hole, connecting rod, crank connecting rod mechanism, motor, hose, main water supply pipe, pressure gauge and water well pipeline interface. The precipitation area, rainfall intensity, average rainfall uniformity coefficient, median diameter of raindrops, terminal velocity and the kinetic energy of rain were measured, and the applicability of the rainfall simulator was discussed. [Results] Rainfall uniformity value was 41%, when the rainfall area was 100 m², which maybe the maximum rainfall area of the simulator. When the rainfall area was 50 m2, water pressure was 0.32 kg/ cm², the rainfall uniformity value was 82% for the maximum rainfall intensity (116.25 mm/ h) and 46% for the minimum rainfall intensity (61.01 mm/ h). Under the same pressure, the rainfall uniformity value range changed from 46% to 82%. The rainfall uniformity value was 82% when the rainfall nozzles moving forward, while the rainfall uniformity value was 80% when the rainfall nozzles moving backward. That means that when the rainfall nozzles moving forward and backward, the rainfall uniformity value was more than 80%, which accorded with the requirements of natural rainfall uniformity. But the average rainfall uniformity value was smaller than 80% when the rainfall nozzle moving left and right, which might be caused by the uneven rainfall. The rain intensity was related to the rainfall median diameter. The measured average median diameter (D50), the average terminal velocity of raindrops, and the average raindrop kinetic energy was 1.67 mm, 3.656 m/ s and 299.4 J/ (m²·cm) respectively, under the different rainfall intensity. The median diameter value presented decreasing trend with the increase of rainfall intensity, but the median diameter of natural rainfall increased with the increase of rainfall intensity, which may be caused by the definite apertures of the three rainfall nozzle. The median diameter decreased with the height increasing, or because the rainfall intensity reached 80 ~ 100 mm/ h the measured median diameter no longer increased. With the increase of rainfall intensity, the terminal velocity of raindrops tended to decrease, but the kinetic energy of raindrops showed an increasing trend. That was probably because that the droplet density was very large, the kinetic energy of rainfall increased with the rainfall intensity increasing. [Conclusions] The device was small, light, in simple operation and convenient movement, especially suitable for field rainfall simulation,which can meet the requirements of the general field and outdoor experiments.