When ultraviolet light-emitting diodes (UV-LEDs) are used for surface disinfection, the UV dose in some areas may exceed the required level but be insufficient in other areas. The most ideal radiation field is that with the same irradiance level at each point. In this study, a universal formula for determining the radiation field was derived, and a corresponding VBA program was coded for the mathematical simulation, analysis, and optimization of the radiation field. The radiation fields of nine UV-LED radiation patterns were simulated and analyzed. The results indicate that for a board with multiple UV-LEDs, the ratio of the radiation distance to the UV-LED spacing and the radiation patterns of the UV-LEDs are the key factors that influence the uniformity of the radiation field. Because of edge effects, a uniform radiation field can be reached only within 80% of the edge length projected directly below the UV-LED board. When the ratio of the radiation distance to the UV-LED spacing is within the range of 3 to 15, the uniformity is good (the ratio of the minimum to maximum values ≥ 81.8%). The radiation pattern with a smaller maximum emission angle is good for a relatively higher ratio of the irradiation distance to UV-LED spacing, and vice versa.