A resolution test device and a method thereof are provided. The resolution test method is adapted for testing a resolution of a camera device. The resolution test method includes providing a graph to the camera device, capturing a test image shot by the camera device, shifting an analyzing window a specific distance in a first direction from a static area to a first area on the test image, analyzing the first area to generate a first high-pass element, shifting the analyzing window back to the static area, shifting the analyzing window the specific distance in a second direction from the static area to a second area on the test image, analyzing the second area to generate a second high-pass element, generating a third high-pass element according to the first and the second high-pass element, and defining the resolution of the camera device according to the third high-pass element.