In recent years, rhenium disulfide (ReS₂) has attracted much attention in polarization dependent photonic applications due to its anisotropic optoelectronic response. To reveal the anisotropic response mechanisms, single crystal layered ReS₂ flake with lateral size of about 10 μm is obtained using mechanical exfoliation method, and the ultrafast carrier dynamics of an individual flake is studied using transient absorption microscopy. The excited carrier concentration of layered ReS₂ flake exhibits obvious polarization dependence of the pump light, which is caused by the anisotropic linear absorption and electron mobility rates in different orientations. These results could provide more references for the application of ReS₂ in polarization sensitive detectors and optoelectronic devices.