Amplified spontaneous emission and parasitic oscillation have many negative influences on the performance of laser resonator.The influences of beam transmission distance in slab and surface reflectivity on amplified spontaneous emission are analyzed.The experiments verifies that bonding Cr4+∶YAG crystal on the ends of slab can effectively restrain the amplified spontaneous emission in the immersion slab resonator,which can improve output energy of the immersion slab resonator.Compared with end-polished slab,the single pulse energy of end-bonded slab increases 38.4%,and the optical-optical conversion efficiency of resonant cavity is 32.3%.