A method of fabricating an active layer thin film by a metal-chalcogenide precursor solution is provided, including the steps of: synthesizing a metal-chalcogenide precursor containing benzyl or benzyl derivative; dissolving the precursor in a solvent to produce a precursor solution, wherein a chalcogen element or compound can be added to the precursor solution to adjust the molar ratio of metal ion to chalcogen; and then applying the precursor solution onto a substrate in a specific coating manner, to form a film of the metal-chalcogenide after a curing process. Thereby, the existing method wherein an amorphous silicon active layer film is fabricated by plasma enhanced chemical vapor deposition (PECVD) is replaced.