[Objective] Designing an artificial rainfall simulator according to the rainfall characteristics required in surface-runoff water quality research in water environment field.[Methods] An artificial rainfall simulator was introduced, which has three specifications of nozzles in order to simulate different rainfall intensity by their open and close.[Results] By means of calibration, the rainfall intensity of this artificial rainfall simulator was 0.3~2.0 mm/min; and in that range of intensity, rainfall uniformity coefficients were all over 85%. The median diameter of raindrop was 1.09~2.25 mm; the maximum diameter was smaller than 6 mm; the raindrop terminal velocity was 2~2.9 mm/s.[Conclusion] The rainfall characteristics was similar to the natural rainfall. This device can be used to simulate the real rainfall.