A kind of normal incidence broadband spectroscopic polarimeter which is easy to adjust the focus, has no chromatic aberration, maintains the polarization and has simple structure. The normal incidence broadband spectroscopic polarimeter can make the probe beam normal incidence and focus on the sample surface by using at least one flat reflector element to change propagation direction of the focused beam. Moreover, the normal incidence broadband spectroscopic polarimeter contains at least one polarizer as to measure the anisotropy or non-uniform samples, such as three-dimensional profile and material optical constants of thin films consisting of the periodic structure. An optical measurement system including the normal incidence broadband spectroscopic polarimeter is also provided.