Great　changes　occurred　in　the　physical　and　chemical　properties　of　the　atmosphere　in　the　North　China　Plain　(NCP)　in　summer　caused　by　PM2.5　dropping　from　58　mu　g/m(3)　in　2015　to　36.0　mu　g/m(3)　in　2019.　In　this　study,　we　first　applied　the　WRF-Chem　model　to　quantify　the　impact　of　PM2.5　reduction　on　shortwave　radiation　reaching　the　ground　(SWDOWN),　planetary　boundary　layer　height　(PBLH),　and　the　surface　concentration　of　air　pollutants　(represented　by　CO).　Simulation　results　obtained　an　increase　of　15.0%　in　daytime　SWDOWN　and　9.9%　in　daytime　PBLH,　and　a　decrease　of　-5.0%　in　daytime　CO　concentration.　These　changes　were　induced　by　the　varied　PM2.5　levels.　Moreover,　the　variation　in　SWDOWN　further　led　to　a　rise　in　the　NO2　photolysis　rate　(JNO(2))　over　this　region,　by　1.82　x　10(-4)similar　to　1.91　x　10(-4)　s(-1)　per　year.　Afterwards,　we　employed　MCM　chemical　box　model　to　explore　how　the　JNO(2)　increase　and　the　precursor　decrease　(CO,　VOCs,　and　NOx)　influenced　O-3　and　HO2　radicals.　The　results　revealed　that　the　photolysis　rate　U)　increase　would　individually　cause　a　change　on　daytime　surface　O-3,　OH,　and　HO2　radicals　by　+9.0%,　+18.9%,　and　+23.7%;　the　corresponding　change　induced　by　the　precursor　decrease　was　-2.5%,　+1.9%,　and　-2.3%.　At　the　same　time,　the　integrated　impacts　of　the　change　in　J　and　precursors　cause　an　increase　of　+6.3%,　+21.1%,　and　+20.9%　for　daytime　surface　O-3,　OH,　and　HO2.　Generally,　the　atmospheric　oxidation　capacity　significantly　enhanced　during　summer　in　NCP　due　to　the　PM2.5　dropping　in　recent　years.　This　research　can　help　understand　atmosphere　changes　caused　by　PM2.5　reduction　comprehensively.