The measuring accuracy of four-beam laser tracking system for 3D coordinate measurement in large degree depends on the arrangement of the interferometers. In this paper the arrangement of four laser tracking interferometers is discussed and three kinds of the optimal arrangements of four laser tracking interferometers are obtained through minimizing the position dilution of precision of the measured point. One of those arrangements of four laser tracking interferometers is considered as the most reasonable arrangement according to the limited receiving angle of the cat's-eye and the restriction on the arrangement in the process of system self-calibration.