A manufacturing method of a glass fiber product is disclosed. A glass fiber resin is provided. The glass fiber resin includes a thermoplastic resin, a glass fiber, and an additive. The amount of the thermoplastic resin is between 30 wt % and 70 wt %, the content of the glass fiber is between 40 wt % and 70 wt % and the amount of the additive is between 0.1 wt % and 15 wt %. A molding process is performed for the glass fiber resin to mold the glass fiber resin into a semi-finished product. A mechanical machining process is performed on the semi-finished product to form at least one recessed structure in the semi-finished product, so as to form a final product.