In order to build right focus window for optical measure equipment in shooting range, a novel method combined with visual perception is proposed. It can cut down compute time and overcome disturbance of background during auto-focus procedure based on image. The image is separated into several sub-images by using pyramid structure. The function and principle of cells in human visual cortex are simulated by Gabor filter and difference of Gaussian (DoG) model. Feature maps from the sub-images are extracted and combined together to get final feature map based on visual perception. The threshold is used to denoise disturbance in the feature map and build regular rectangle focus window area by spreading boundary. After plenty of experiments，the results show that this method can build focus window rapidly with exact size and right position for the target in image. And it is available for every kinds of focus states, especially for deep-defocus state. To deal with the image of 720 pixel×576 pixel, the compute time is less than 130 ms. The proposed method can construct steady and exact focus window during the whole focus procedure, which satisfies the practical demand of shooting range and is of great and wide value for engineering application.