An image processor and an image combination method thereof are provided. The image processor includes a processing unit for performing the image combination method, and a storing unit for storing an original image and an output image. The image combination method includes the following steps. First, the original image is received from the storing unit. A first processing procedure scales down the original image to generate a first image. A second processing procedure crops the original image to generate a second image. The first image and the second image are combined to form and then be outputted the output image. Accordingly, the image processor and the image combination method are capable of providing the overview and local detailed content of the original image at the same time.