A system for measuring lens deflection of an electronic device includes a first shape, an image processing module, a first angle calculation module, and a second angle calculation module. The first shape is formed by edges of an ideal image captured that corresponds to a correctly mounted lens in the electronic device. The image processing module processes a currently captured image to acquire a second shape formed by edges of the present image. The first shape and the second shaped are imposed on each other. The first angle calculation module computes a first angle according to a rotation angle of the second shape relative to the first shape. A second angle calculation module computes a second angle according to a translating distance of the second shape relative to the first shape.