Agriculture　and　vehicles　are　important　ammonia　emissions　sources　in　rural　and　urban　areas,　respectively.　A　comparative　study　of　their　environmental　impacts　is　of　great　significance　for　the　scientific　formulation　of　emission　reduction　strategies.　However,　there　is　currently　a　lack　of　research　on　the　differential　impacts　of　agricultural　and　vehicular　NH3　emissions.　This　study　established　a　NH3　emission　inventory　with　1　km　resolution　for　fertilizer,　livestock　and　vehicles　based　on　the　emission　factor　method,　and　analyzed　their　spatial　and　temporal　distribution　characteristics.　Further,　WRF-CAMx-PSAT,　combined　with　Brute-Force　method　was　used　to　simulate　the　emission　reduction　scenarios　of　agricultural　and　vehicular　NH3　in　January　and　June　2017　to　investigate　the　differential　effects　of　different　NH3　emission　sources　on　atmospheric　PM2.　5.　Results　show　that　the　ammonia　emissions　from　fertilizer,　livestock　and　vehicles　in　Beijing-Tianjin-Hebei　were　31.　0　×　104　t,　44.　7　×　104　t,　and　0.　8　×　104　t,　respectively,　in　2017.　From　the　perspective　of　emission　reduction　effect,　when　agricultural　and　vehicular　NH3　emission　was　gradient　reduced　by　10%,　30%,　50%,　70%,　and　100%,　respectively,　NH4+　showed　a　nearly　linear　change,　however,　SO24-　and　NO3-　showed　a　non-linear　decreasing　trend.　Influenced　by　emissions,　the　average　change　rates　(-　16.　3%,　-　4.　3%,　and　-　37.　3%)　of　NH4+　,　SO24-　,　and　NO3-　concentrations　under　the　agricultural　NH3　reduction　scenarios　were　significantly　higher　than　those　(-　1.　7%,　-　0.　2%,　and　-　4.　3%)　under　the　vehicular　NH3　reduction　scenarios.　However,　from　the　perspective　of　emission　reduction　efficiency,　the　opposite　phenomenon　was　found.　To　analyze　the　emission　reduction　efficiency,　the　NH3　emission　reduction　air　quality　improvement　efficiency　index　was　proposed　and　defined　as　the　change　in　PM2.　5　concentration　under　the　unit　(104　tons)　of　NH3　emission　reduction.　By　comparison,　it　is　found　that　the　air　quality　improvement　efficiency　of　vehicular　NH3　emission　reduction　was　significantly　higher　than　that　of　agricultural　NH3　emission　reduction,　with　a　difference　of　1.　0　-　3.　2　times　and　1.　2　-　2.　3　times　in　January　and　June,　respectively.　The　results　of　the　study　can　provide　scientific　basis　for　the　optimal　prevention　and　control　of　air　pollution.　©　2023　Beijing　University　of　Technology.　All　rights　reserved.