The simulated annealing(SA) arithmetic was used in the optimized designing for several wavelength in soft x-ray region and the optimized optical parameters was gained,including the optimized period thickness,thickness ratio and peak reflectance.According to the design results,the mirrors were fabricated and were measured in the device of Beijing synchronization radiation.It shows that the simulated annealing method is indeed practical for the design of multi-layer mirrors in soft x-ray region.