We systematically studied the effect of p-electrode patterns on the optical properties and -3dB bandwidth of micro-size LEDs. The current spreading distribution can be effectively improved via adjusting the number and shape of the p-electrode branch, thus increasing the injection saturation current density and decreasing the series resistance. Compared with the micro-size LED using a disk p-electrode, the saturation light output power and -3dB bandwidth of the micro-size LED using a six-branches spiral p-electrode increase by 39.48% and 76.61%, respectively. Such a p-electrode pattern is a promising solution for micro-size LED applications in both illumination and visible light communication systems.