The design, fabrication and characterization of the X-ray supermirrors are discussed in this paper. Using the local optimization method of simplex algorithm and the global one of simulated annealing algorithm with different initial multilayer structures, we designed the broad angular band supermirrors with different grazing incidence angle intervals at the energy of 8.0 keV (the Kα line of Cu) and the broad energetic band supermirrors with different energy intervals at fixed grazing incidence angles. The fabricating techniques for depositing non-periodic multilayers are also studied. The W/C and W/Si supermirrors are deposited on silicon substrates and characterized by a high resolution X-ray D1 diffractometer from Bede Company, UK. Choosing the interface roughness and the densities of the materials as independent variables, some measured reflectivity curves are fitted using the Debye-Waller factor with interface roughness. The experimental results show that the optical performances of the fabricated supermirrors are in agreement with the designed ones. The design, fabrication and characterization of the X-ray supermirrors are discussed in this paper. Using the local optimization method of simplex algorithm and the global one of simulated annealing algorithm with different initial first-layer structures, we designed the broad angular band supermirrors with different grazing incidence angle intervals at the energy of 8.0 keV (the Kα line of Cu) and the broad energetic band supermirrors with different energy intervals at fixed grazing incidence angles. The fabricating techniques for depositing non-periodic multilayers are also studied. The W / C and W / Si supermirrors are deposited on silicon substrates and characterized by a high resolution X-ray D1 diffractometer from Bede Company, UK. Choosing the interface roughness and the densities of the materials as independent variables, some measured reflectivity curves are fitted using the Debye- Waller factor with interface roughness. The experimental results show that the optical performances o f the fabricated supermirrors are in agreement with the designed ones.