A lens measuring device and method applied therein. The lens measuring device includes a light source, a first polarizer, a second polarizer, and an image analysis module. The method includes enabling the light source to orderly pass through the first polarizer, a lens to be measured, and the second polarizer to generate a light beam to be measured, and then enabling the image analysis module to analyze image-related information of the light beam to be measured, consequently deducing the structural center and energy distribution of the lens to be measured, and then further analyzing errors in polarity and skewness of the lens to be measured. By applying a common light source, the method is spared complicated correction that is otherwise required when a conventional collimating laser light source is applied, and the method can also easily and simultaneously test a plurality of lenses to be measured.