Abstract: The transmitted wave front aberration is the key factor which restricts the further development of high average power solid-state lasers. This work analyses the error source of transmitted wave front for end surface, and a scheme of slab processing is purposed according to technology requirement of Nd:YAG crystal slab for high average power solid-state lasers. With the new type complex pad, fixture of slab and new polishing process, the problem of poor controllability of surface figure and wedge angle in continuous polishing has been solved. The processing results show that the PV of end surface transmitted wavefront aberration reached 0.74 for 150 mm30 mm2.5 mm specification Nd:YAG crystal slab. The processing precision satisfies the application requirement of high average power solid-state lasers.