Due to the influence of the background and the other factors,infrared small target is easy to be covered,thus,infrared small target detection is always a difficulty in infrared image processing.An infrared small target detection method based on area gradient was proposed. Through analyzing the features of IR image,the background noise of the image was suppressed by morphology.The positions of target points were located by using gray value,and then the sizes of target points were decided by using area gradient information.The simulation images of different SNR were processed by this method,and this method is compared with K-means clustering and morphological algorithm.The results show that three methods can all effectively detection the target in the condition of high SNR,but only the proposed algorithm can detected the small target in low SNR image.