It is an important task to detect the small targets in a sequence of images against complex background. An algorithm of small target detection based on pattern lateral inhibition is proposed.Small target detection in complex background is considered as a problem of finding the special patterns in similar patterns. The special patterns are enhanced with the Lateral Inhibition network. At the same time,multi-level processing is presented to improve treatment effects.The performances of several traditional filters and the method in this paper are compared.Two defininitions of SCR and SCR gain are defined to evaluate the performance of the approach Experimental results show that the approach proposed is effective in detecting the small targets in clutter.