This　paper　investigates　the　characteristics　of　selective　catalytic　reduction　(SCR)　with　a　V2O5-WO3/TiO2　catalyst　by　studying　the　key　parameters　and　determining　a　method　for　controlling　ammonia　injection　with　a　sample　test　bench.　Four　parameters　are　defined　and　adopted　to　represent　the　characteristics　of　nitrogen　oxides　(NOx)　and　the　ammonia　reaction.　The　effects　of　NH3/NOx　ratio　(NSR),　catalyst　temperature,　and　ammonia　injection　period　on　NOx　conversion　efficiency　and　ammonia　slip　are　investigated.　The　correlation　between　ammonia　slip　and　ammonia　saturation　storage　level　is　studied.　The　experimental　results　show　that　the　ammonia　saturation　storage　level　has　a　great　impact　on　NOx　reduction　and　ammonia　slip.　The　NOx　conversion　efficiency　and　ammonia　slip　strongly　depend　on　the　ammonia　saturation　storage　level.　Under　such　conditions,　the　NOx　conversion　efficiency　is　best　when　the　ammonia　saturation　storage　level　is　68.2　similar　to　73%,　and　the　value　reaches　75%　before　ammonia　slip.　Pulse　injection　improves　the　NOx　conversion　efficiency　and　limits　ammonia　slip.　Comprehensive　comparison　shows　that　the　injected　ratio　of　NH3/NOx　is　first　larger　and　then　smaller　than　is　beneficial　for　the　rapid　improvement　of　NOx　conversion　efficiency;　the　appropriate　NH3/NOx　ratio　and　continuous　injection　time　must　be　controlled,　or　it　is　easy　to　cause　ammonia　slip.　Therefore,　a　control　algorithm　based　on　ammonia　storage　saturation　level　has　been　proposed.　According　to　the　difference　between　the　actual　value　of　ammonia　storage　saturation　and　the　target　value,　the　controller　corrects　the　injection　of　urea　to　achieve　control　of　ammonia　storage　saturation　level.　The　period　of　pulse　injection　has　little　influence　on　the　mean　value　of　NOx　at　the　outlet;　however,　it　affects　the　peak　level　of　NOx　and　ammonia　slip.　Using　varied　period　pulse　injection　further　improves　the　NOx　conversion　efficiency　and　restrains　ammonia　slip.　The　outlet　level　of　NOx　can　be　reduced　by　adopting　a　suitable　ammonia　pulse　injection　interval.