Abstract: To design the monochorator beamlines of synchrotron radiation, develop X-FELs and make X-ray diagnoses of inertia confinement fusion as well as simulate dynamic process in extreme physical conditions, a useful tool and a platform, X-LAB, for optical design, optimization and simulation with the independent intellectual property rights was developed. With friendly interface, X-LAB has the functions of sequence ray-tracing, vector diffraction simulation and layout drawing of complex micro-structure optical elements. Also, it is easy to operate and can provide accustomed service, characteristic functions for users to freely design, optimize an optical system. Currently, X-LAB has been applied in designs and simulations of the 3B1 monochromatic beamline in Beijing Synchrotron Radiation Facility with spectral resolution 1000 and spectral range 10~100 eV, the X-ray diagnosis optical systems of inertia confinement fusion and dynamic process in extreme physical conditions, the KB microscope with spatial resolution up to 6 μm, and the layout drawing of photon sieves.