A high accuracy micro-focusing system was designed to improve the light spot focusing quality of the X-ray beam-line for Photo-emission Electron Microscope (PEEM) in Shanghai Synchrotron Radiation Facility(SSRF). The layout of PEEM beam-line of the SSRF was introduced and basic parameters of optics of the micro-focusing system were presented. Two Kirkpatrick-Baez mirrors (KB mirror) were adopted to finish the design of micro-focusing system. The design scheme of a key component-posture adjusting mechanism in the system was introduced. Namely， a three vertical linear driving equipment and a two horizontal linear driving device were combined to implement five-dimensional adjustment of the system. The working principle and process of the posture adjusting mechanism were introduced， and the overall design scheme of micro-focusing system were analyzed deeply. The mechanical performance of KB mirror system was tested， and the testing results of the horizontal adjusting mechanism and the pitch motion of first mirror were given. That the resolution and repeat accuracy of horizontal adjusting mechanism are 0.6 μm and 0.85 μm respectively， and those of pitch motion are 0.4″ and 0.5″ respectively， which are better than that of the technical requirements. The other parameters were tested as well， and the results also satisfy the technical requirements. The realization of technical targets of KB mirror system guarantees the high quality focusing of PEEM bean-line.