Aiming at the strong real-time demand of image processing in the focus detection system of projection lithography machine, a focus detection image real-time processing system based on SOPC is designed with FPGA chip as the carrier. Firstly, the MicroBlaze embedded soft core is used to execute the image processing algorithm, and the system scheme verification and algorithm debugging can be carried out without changing the hardware architecture; Then, using the scheme of software and hardware cooperation, the algorithm is transplanted to FPGA hardware to accelerate the focus detection process. The FPGA chip carries out data interaction between software and hardware through Axi bus, and the off chip is interconnected with the worktable through optical fiber interface to complete the high-speed upload of focus detection results. The experimental results show that the system runs stably, and it takes 104 μs to complete the entire focus detection process, and the software-hardware collaboration is about 1700 times faster than the soft-core implementation.