The perovskite catalysts have been studied for the purpose of replacing noble metal catalysts in auto exhaust control. However, the activity is not enough for the engineering applications. In this work, La was taken as a basic material in A site. A variety of transition metals such as Cu, Fe, Mn. Co and Al in B site have been studied to test the catalytic activities in NO reduction. Cu in B site showed high activity and the highest activity was achieved when 10% of cupper in B site was replaced by Mn, i.e., LaCu_0.9Mn_0.1O₃.