Although the anisotropy and strategies for the modulation of the anisotropy in ReS2 have been widely reported, a comprehensive study on the inherent electronic anisotropy of ReS2 is still absent to date; therefore, the mechanism of anisotropy evolution is ambiguous as well. In this study, we have conducted a systematic investigation on the evolution of electronic anisotropy in bilayer ReS2, under the modulation of charge doping levels and temperature. It is found that the adjustability of electronic anisotropy is largely attributed to the angle-dependent scattering from defects or vacancies at a low doping level. At a high doping level, in contrast, the inherent electronic anisotropy can be recovered by filling the traps to attenuate the influence of scattering. This work renders insights into the exploration of electronic anisotropy in 2D materials.