A preprocess algorithm based on variogram function for IR dim target detection is proposed.According to the different variogram function values of IR target,the background and the noise,it is effective and reliable to analysis the texture of the IR image using the variogram function,and it is feasible to research on filtering algorithms based on variogram function for target detection.The experiment results show that the method can effectively suppress the background clutter which has strong spatial and temporal correlation,and increases target SCR.