A new edge detection algorithm is proposed in the infrared image processing.The algorithm first wipes off Images which obtained by the Otsu algorithm isolated pixels and close operation.Then uses Sobel operator edge detection.Then,added the images obtained with the use Sobel operator directly to the original image for the edge detection images.Finally used MATLAB has carried on the simulation to the digital image and the infrared imagery.The simulation result indicated that the algorithm has improved Sobel operator only to vertical and horizontal direction sensitive,the other direction not sensitive.It can be demonstrated that the performance of the traditional Sobel detection operator is improved through the experiment t and the detection accuracy.And it is not only suitable for the digital image is also suitable for the infrared imagery.