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 multi-pinholes using fewer pinholes. This method overcomes the limit on large TC detection by multi-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.