Activated carbon-supported Ru-based catalyst and A301 iron catalyst were prepared, and the influences of reaction temperature, space velocity, pressure, and H-2/N-2 ratio on performance of iron catalyst coupled with Ru catalyst in series for ammonia synthesis were investigated. The activity tests were also performed on the single Ru and Fe catalysts as comparison. Results showed that the activity of the Ru catalyst for ammonia synthesis was higher than that of the iron catalyst by 33.5%-37.6% under the reaction conditions: 375-400 degrees C, 10 MPa, 10000 h(-1), H-2 : N-2 = 3, and the Ru catalyst also had better thermal stability when treated at 475 degrees C for 20 h. The outlet ammonia concentration using Fe-Ru catalyst was increased by 45.6%-63.5% than that of the single-iron catalyst at low temperature (375-400 degrees C), and the outlet ammonia concentration increased with increasing Ru catalyst loading.