Beam coherent combination of two photonic crystal fiber (PCF) lasers is experimentally studied by using self-imaging resonator technique, and phase-locking of the two PCF lasers is achieved. Clear and stable interference strips are observed even without a filter in high-power operation and in environmental noise condition. The advantages of PCF laser in coherent combination over the conventional double-cladding fiber (DCF) are demonstrated. Experiments also show that the reflectivity of coupling output mirror affects coherent output power. The slope efficiencies of two PCF lasers running in in-phase mode are 63.8%, 61.6% and 60.2% for the reflectivity 5%, 10% and 15% of the reflector, respectively. The maximum coherent output power of 95.8W and the combination efficiency of 90.2% are obtained when the pump power is 150 W for the reflectivity of 5%. No thermo-optical problems occur during the experiments, which means that a higher coherent power can be further achieved by using this technique.