Abstract: The rapid development and realization of X-ray Free Electron Laser (XFEL) has advanced the femtosecond X-ray science in many research fields including physics, chemistry,materials science and structural molecular biology. By using the Optical pump/X-ray probe technique, one can track the dynamics of the system at varying timescale upon the excitation. X-ray absorption and emission spectroscopies, X-ray diffraction and scattering are typical X-ray techniques for probing the dynamic changes in electronic and geometric structures. Here we summarized the recent progresses of femtosecond X-ray science in chemistry.