It is found that the interaction between the two transition metal Mn, Co ions on B-site and their Redox property are the important factors influencing the NO-selectivity in ammonia oxidation. The NO-selectivity is related to the redox ability of Mn 3 + -> Mn 4 + or Co 2 + -> Co 3 + , which could be promoted by doping a small amount of foreign transition metal ions on B-site of matrix samples, but not for the sample with the composition of y=0.5.