Phase locking of a two-dimensional fiber laser array is experimentally demonstrated by using a self-imaging resonator and a spatial filter. The stable beam profiles of in-phase mode and out-of-phase mode are observed by controlling the position of spatial filter. The phase locking fiber array with in-phase mode has produced 26W coherent output. An antisymmetric eigenmode is also observed in our experiments. The phase locking is not sensitive to power variations among the pump beams and the configuration has the ability to repair a missing element.