The invention discloses a variance and smoothness-based definition evaluation method for the same content image, and the method comprises the steps: firstly, obtaining a group of to-be-processed images, setting the number of the to-be-processed images as N, carrying out the graying processing of the to-be-processed images, and obtaining the gradation images of the group of to-be-processed images;calculating the variance scalar and the smoothness scalar of each gray level image to obtain the variance scalar and the smoothness scalar of the group of images; and finally obtaining variance scalarand smoothness scalar change curves of the group of pictures by utilizing a plot () function in Matlab, wherein the picture with the maximum variance scalar and smoothness scalar is the picture withthe highest definition in the same group of content images. According to the invention, the problems of poor stability and low sensitivity of an image definition evaluation method in the prior art aresolved.