Ozone　pollution　in　Handan　has　become　severe　in　recent　years　and　in　the　summer　of　2018,　the　average　maximum　daily　8-hour　average　ozone　concentration　in　Handan　was　175　μg·m-3　with　a　maximum　of　257　μg·m-3.　Ozone　concentrations　exceeded　the　National　Air　Quality　Grade　Ⅱ　Standard　in　59%　of　cases.　In　this　study,　the　H2O2/HNO3　indicator　was　applied　to　analyze　summertime　ozone　sensitivity　in　Handan　using　the　WRF-CMAQ　modeling　system.　The　results　showed　that　H2O2/HNO3　was　more　appropriate　than　other　ozone　indicators,　both　theoretically　and　based　on　simulation　outputs.　The　good　simulation　effect　of　CMAQ　on　H2O2　and　HNO3　was　attributed　to　fine　emission　inventory　and　grid　resolution.　The　H2O2/HNO3　simulation　results　showed　that　the　relative　importance　of　a　VOCs-limited　regime　decreased　month　by　month;　a　VOCs-NO
x
-mixed-limited　regime　was　dominant　in　June;　and　a　NO
x
-limited　regime　was　more　dominant　in　July　and　August　than　in　June.　The　remarkable　spatial　difference　in　VOCs　and　NO
x
　emission　ratios　among　the　counties　of　Handan　led　to　differences　in　ozone　sensitivity.　The　VOCs-limited　regime　was　concentrated　in　counties　where　VOCs/NO
x
　emission　ratios　were　lower　than　1.7.　Southern　counties　had　a　NO
x
-limited　regime,　where　VOCs/NO
x
　emission　ratios　were　higher　than　6.9.　Counties　with　VOCs/NO
x
　emission　ratios　varying　from　1.7　to　6.9　were　more　susceptible　to　both　VOCs　and　NO
x
.　According　to　these　results,　the　transition　range　of　HCHO/NO2,　O3/HNO3,　and　O3/NO
x
　ratios　were　adjusted　to　0.35-0.6,　20-35,　and　10-25　respectively.　Adjusting　the　transition　range　of　H2O2/(O3+NO2)　was　not　effective,　indicating　that　this　indicator　may　not　be　applicable　to　Handan.