A spectrometer module and a fabrication method thereof are provided. The fabrication method includes the steps of: providing at least one substrate; and forming at least one positioning side and at least one optical component of the spectrometer on the at least one substrate by a microelectromechanical systems (MEMS) process. The spectrometer module fabricated by the fabrication method includes a plurality of substrates and at least one optical component. At least one of the substrates has at least one positioning side, and the at least one optical component of the spectrometer is formed on at least one of the substrates. The positioning side and the optical component are fabricated by a MEMS process.