The invention provides a measuring method of minimum exposure energy. The measuring method comprises the following steps: S1, providing a wafer and coating the wafer with a photoresist layer; S2, respectively exposing a plurality of areas preset on the photoresist layer according to a plurality of preset time periods by using a wafer edge exposure device, wherein each area corresponds to a sole time period; S3, developing the exposed photoresist layer by using a developing process so as to form a pattern corresponding to each area; and S4, obtaining a pattern corresponding to each time periodby using a post-development inspection process and processing to obtain a corresponding relation between each time period and the corresponding pattern and the minimum exposure energy. The measuring method of minimum exposure energy has the beneficial effects that the minimum exposure energy of photoresist can be obtained without the support of an exposure machine, the lighting condition of the wafer edge exposure process can be optimized according to the obtained minimum exposure energy, and the generation of photoresist residue can be avoided.