The　concentrations　of　atmospheric　pollutants　PM2.5,O3,SO2,NO2,and　CO　together　with　the　meteorological　factors　of　temperature(T),relative　humidity(RH),wind　speed,and　other　relevant　data　in　Tangshan　from　2015　to　2021　were　collected　to　study　the　variation　characteristics　of　PM2.5　and　O3　at　different　periods　in　Tangshan　City　in　the　past　seven　years　and　their　influencing　factors,to　discuss　the　contributions　of　air　mass　transport　to　PM2.5　and　O3　pollution,and　to　reveal　the　synergistic　influence　mechanism　of　PM2.5　and　O3　on　atmospheric　compound　pollution　by　using　correlation　analysis　and　backward　trajectory　cluster　analysis　techniques.　The　results　showed　that　PM2.5　concentrations　in　Tangshan　decreased　year　by　year　from　2015　to　2021,whereas　O3　concentration　showed　a　unimodal　trend,with　the　peak　appearing　in　2017.　Both　PM2.5　and　O3　concentrations　showed　obvious　seasonal　variation　trends;PM2.5　was　characterized　by　the　highest　concentration　in　winter　and　the　lowest　concentration　in　summer,whereas　O3　was　characterized　by　the　highest　concentration　in　summer　and　the　lowest　concentration　in　winter.　In　addition,the　diurnal　variation　in　PM2.5　showed　a　bimodal　distribution,with　the　peak　occurring　during　the　morning　and　evening　on　weekdays,and　O3　showed　a　unimodal　distribution,with　the　peak　value　appearing　during　the　period　with　strong　ultraviolet　radiation　in　the　afternoon.　PM2.5　had　a　significant　positive　correlation　with　SO2,NO2,and　CO,whereas　O3　had　a　significant　positive　correlation　with　radiation　and　temperature.　Under　the　different　pollution　conditions,PM2.5　and　O3　were　affected　by　air　mass　transports　from　different　directions.　Being　impacted　by　various　factors,the　synergistic　effect　of　PM2.5　and　O3　on　atmospheric　compound　pollution　showed　an　obvious　negative　effect　in　winter,whereas　there　was　an　obvious　positive　effect　in　spring,summer,and　autumn.　Under　the　backgrounds　of　different　pollutions,when　the　concentration　of　PM2.5　exceeded　150　μg·m-3,the　synergistic　effect　of　PM2.5　and　O3　showed　an　obvious　negative　effect.　©　2024　Science　Press.　All　rights　reserved.