As a typical high-power solid-state laser, high average power zigzag slab lasers achieved great progress in past two decades. Which fields got many innovations, such as face-pumped slab amplifier, multi-segment bonded slab structure, high-brightness pumped Yb: YAG slab amplifier and so on. This paper reviewed the technology progress of the slab lasers, including its design principles, transmission power amplification rules and various improvement methods for optimizing performance.On the basis of the general discussion on the laser power calibration capability of the slats, the technical development trend of improving the output power and beam quality was analyzed and discussed. It was expected that there will be considerable development space for high average power slab laser technology in the future.