The invention discloses a method for fabricating a hollowed-out board of a flexible printed circuit (FPC) by laser windowing. The method comprises the following steps: (a) pure copper plate cutting; (b) first chemical treatment, namely carrying out surface chemical treatment on the pure copper plate; (c) dry film laminating, namely pressing the dry film on the front surface of the pure copper plate; (d) compounding of a reverse cover film, namely compounding the front surface of the reverse cover film and the reverse surface of the pure copper plate; (e) ultraviolet exposure; (f) developing; (g) etching; (h) film removal; (i) second chemical treatment, namely carrying out surface chemical treatment on a line part; (j) compounding of the front cover film, namely compounding the reverse surface of the front cover film and the front surface of the line part; and (k) laser windowing, namely carrying out windowing treatment on the reverse cover film with laser to form the hollowed-out board. According to the method disclosed by the invention, the steps of developing, etching and film removing are firstly carried out; and then windowing treatment is carried out on the reverse cover film, so that an etching solution can be prevented from entering inside the hollowed-out board while etching and poor etching is avoided. Therefore, the stability and the quality of the product are improved; and the raw materials are reduced.