A lens module distortion measuring system configured to measure the distortion of a lens module including: a light source configured to emit light rays; a diffusing panel configured to diffuse the light rays; a substantially opaque shielding plate beneath the diffusing panel, the shielding plate defining a regular matrix of light-passing holes capable of allowing some of the diffused light rays to pass therethrough; an image capturing device configured to capture a image of the shielding plate as viewed through the lens module, the image comprising an array of light spots corresponding to the light-passing holes; and a computing unit electrically connected to the image capturing device and configured to analyze the light spots of the image and thereby determine the distortion of the lens module.