This paper introduces a new nondestructive method-continuous wave electro-optic probing (CWEOP), which we have applied to detect the electrical field distribution of GaAs/AlGaAs LED array. The experiment results reflect the direction of injected current, the spreading of charge carriers and the homogeneity of the light emission by comparing the field distribution of each unit. The principle, experimental setup of the method and the experimental results and discussions to them are given. The comparison between the result of computer-aided simulation and the experiment one is also given at last.