Coherent beam combination of Yb-doped fiber laser array is studied experimentally by spatial filtering to passive phase locking.The system of coherent beam combination by Yb-doped fiber amplifiers array in two-dimensional distribution is built.The four polarization maintaining Yb-doped fiber amplifiers are developed.By optical feedback of in-phase signal,the in-phase output of all amplified lasers is achieved and two-dimensional far-field stable interference pattern is obtained.The coherent contrast ratio is up to 91.7% and coherent coupling efficiency is 94.5%.Coherent output of multi-longitudinal modes is also observed in phase locking.