The　aim　of　this　work　is　to　study　the　effect　of　Sr　substitution　on　the　redox　properties　and　catalytic　activity　of　La2-xSrxNiO4　(x　=　0.0-1.2)　for　NO　decomposition.　Results　suggest　that　the　x　=　0.6　sample　shows　the　highest　activity.　The　characterization　(TPD,　TPR,　etc.)　of　samples　indicates　that　the　x　=　0.6　sample　possesses　suitable　abilities　in　both　oxidation　and　reduction,　which　facilitates　the　proceeding　of　oxygen　desorption　and　NO　adsorption.　At　temperature　below　700　degrees　C,　the　oxygen　desorption　is　difficult,　and　is　the　rate-determining　step　of　NO　decomposition.　With　the　increase　of　reaction　temperature　(T　＞　700　degrees　C),　the　oxygen　desorption　is　favorable　and,　the　active　adsorption　of　NO　on　the　active　site　(NO　+　V-o　+　Ni2+　-＞　NO--Ni3+)　turns　out　to　be　the　rate-determining　step.　The　existence　of　oxygen　vacancy　is　the　prerequisite　condition　for　NO　decomposition,　but　its　quantity　does　not　relate　much　to　the　activity.