A laser system that can produce 0.4 J/10 ns/10 kHz-4 kW using a coherent beam combination with stimulated Brillouin scattering phase conjugate mirrors (SBS-PCMs) is proposed. The 4 kW coherent beam combination laser system consists of a front-end system, a pre-amplifier module, a coherent beam divider/combiner, and 4 main amplifier modules. The front-end system produces 1064 nm @ 10 kHz laser pulses, and it is amplified by the pre-amplifier. After the pre-amplifier module, the laser beam is divided into 4 sub-beams. Each sub-beam is amplified by the main amplifier module in a double-pass configuration and reflected by SBS-PCMs. Sub-beams are combined by a coherent beam combiner, and the output of the total system is designed to be 4 kW. With this 4 kW laser module, high-speed 2D holographic laser processing will be utilized.