Phase locking for two ytterbium-doped large-core fiber lasers has been demonstrated by using a self-imaging confocal resonator with a spatial filter. Steady high-contrast interference stripes are observed. The visibilities of coherent and incoherent stripes are 59% and 6%, respectively. The measured width of the central strip is in good agreement with the calculated result. For in-phase mode, the output power of the phase-locked fiber laser array is up to 113 W and corresponding slope efficiency is 38.5%.