Environmental　management　has　evolved　from　a　vertical　command　and　control　management　model　to　a　more　collaborative　one.　A　series　of　public　administration　studies　take　the　field　of　environmental　policy　as　an　important　background　for　understanding　collaborative　governance,　yet　the　theoretical　and　empirical　study　of　environmental　collaborative　governance　is　relatively　under-developed.　This　article　begins　to　fill　the　research　lacuna　through　the　investigation　of　air　pollution　collaborative　governance　practice　in　Jing-Jin-Ji　and　surrounding　areas.　Based　on　the　panel　data　of　58　regional　cities　from　January　2016　to　March　2019,　a　difference　in　difference　quasi-natural　experiment　design　is　employed　to　explore　the　effect　of　environmental　collaboration　under　Chinese　authoritarian　regime.　The　analysis　shows　that　environmental　collaboration　has　a　positive　impact　on　air　quality　and　exhibits　different　effects　on　primary　and　secondary　pollutants.　Specifically,　it　has　a　greater　influence　on　the　emission　reduction　of　NO2　compared　to　SO2　and　CO,　the　positive　effects　of　environmental　collaboration　on　PM2.5　and　PM10　pollutants　are　significant,　and　there　is　no　statistically　positive　impact　on　O3　control.　The　time　trend　effect　of　environmental　collaboration　varies　among　pollutants,　it　presents　positive　effects　on　air　quality　improvement　and　secondary　pollutant　control　(e.g.,　PM2.5,　PM10)　after　the　fourth　month,　the　mitigation　effect　of　environmental　collaboration　on　primary　pollutants　represented　by　NO2　is　more　significant　and　constant　in　the　sixth　month.　However,　the　time　trend　effect　of　environmental　collaboration　has　gradually　weakened.　This　paper　concludes　with　discussions　on　the　direction　and　implications　of　improving　the　performance　and　sustainability　of　environmental　collaboration　in　China.　©　2020