The distribution of current diffusion of the quaternary AlGaInP LED has been simulated by finite element method to study the effect of electrode shape on the current spreading layer GaP. By comparing traditional circular-shape with cross-shape, arrow-shape, floriated-shape and gammadion-shape electrodes, we found that the electrode shape has an important effect on the output efficiency of light, and the light extraction efficiency of gammadion electrode is the highest. As the area of the whole electrode has an effect on the output efficiency, by optimizing the width of the electrode, the light extraction efficiency will be upgraded. For the gammadion electrode, when the width equals to 6.2204 μm, its light extraction efficiency is the highest, which is more than twice that of the traditional round electrode’s.