Iron-based perovskite-type compounds modified by Ru were prepared through sol-gel process to study its catalytic activity of NO_x direct decomposition at low temperature and evaluate the conversion of NO under the experimental conditions. The catalytic activity of La_ 0.9Ce_ 0.1Fe_ 0.8-nCo_ 0.2Ru_nO_3 (n=0.01,0.03,0.05,0.07,0.09)series for the NO, NO-CO two components, CO-HC-NO three components were also analyzed. The catalytic investigation evidenced that the presence of Ru is necessary for making highly activity in decomposition of nitric oxide even at low temperature(400 ℃)and La_ 0.9Ce_ 0.9Fe_ 0.75Co_ 0.2Ru_ 0.05O_3 (n=0.05) has better activity in all the samples, the conversion of it is 58.5%. With the reducing gas(CO,C_3H_6)added into the gas, the catalyst displayed very high activity in decomposition of NO and the conversion of it is 80% and 92.5% separately. Iron-based perovskite-type compounds modified by Ru were prepared through sol-gel process to study its catalytic activity of NO_x direct decomposition at low temperature and evaluate the conversion of NO under the experimental conditions. The catalytic activity of La_ 0.9Ce_0.1Fe_0.8 The series of the NO, NO-CO two components, CO-HC-NO three components were also analyzed. The catalytic investigation evidence that that the presence of Ru is necessary for making highly activity in decomposition of nitric oxide even at low temperature (400 ° C) and La_ 0.9Ce_ 0.9Fe_ 0.75Co_ 0.2Ru_ 0.05O_3 (n = 0.05) has better activity in all the samples, the conversion of it is 58.5%. With the reducing gas (CO, C_3H_6) added into the gas, the catalyst displayed very high activity in decomposition of NO and the conversion of it is 80% and 92.5% separately.