In recent years,ozone (O₃) pollution has become increasingly severe,which has proved to be the bottleneck of air quality control in Wuhan.Clarifying the nonlinear relationship between ozone and its precursors is the basis for ozone pollution control.To address this,an observation-based model was used to calculate relative incremental reactivity (RIR) and ozone formation potential based on online observation data of O₃ and its precursors collected by Wuhan city station during April to September 2018.The results showed that O₃ possessed obvious temporal variation on both seasonal and diurnal scales,and was subject to O₃ precursors as well as meteorological conditions.The average volume fraction of volatile organic compounds (VOCs) was 32.5×10^-9 during the observation period.Alkanes were the dominant VOCs in Wuhan,followed by oxygenated VOCs (OVOCs) and halogenated hydrocarbons.The reductions of VOCs and NO_x would respectively result in a significant drop and an increase of ozone formation potential.It indicated that Wuhan was under the VOCs-limited regime during the observation period.Among the anthropogenic VOCs,m/p-xylene and o-xylene had the highest RIR,thus were the major components affecting the formation of ambient ozone in Wuhan.