We propose an efficient method for characterizing the orbital angular momentum （OAM） of an optical vortex with a large topological charge （TC） through distinguishing the interference pattern of the non- uniformly-distributed nmlti-pinholes using fewer pinholes. This method overcomes the limit on large TC detection by nmlti-point interferometer and can be used to probe optical vortices with arbitrary sizes. In addition, it also has potential application in measuring light beam with OAM from astronomical sources.
