A method for measuring a thin film thickness is provided. The method includes the following steps: providing a plurality of structures, each including a semiconductor substrate, a thin film, and a metal layer; measuring resistances of the metal layers of the plurality of structures and thicknesses of the thin films of the plurality of structures to obtain a plurality of resistance values and a plurality of corresponding thickness values; establishing a thickness-resistance table based on the plurality of resistance values and thickness values; providing a structure to be tested including a semiconductor substrate, a thin film, and a metal layer; and measuring resistance of the metal layer of the structure to be tested to determine a thickness value of the thin film of the structure to be tested according to the thickness-resistance table.