<p>The heterogeneous uptake of hydroxyl peroxy radicals (HO<sub>2</sub>) on aerosol has been proposed to be a significant sink of HOx, thus could influence the atmospheric oxidation capacity. Accurate calculation of the uptake coefficient γHO<sub>2</sub> is the key to quantifying its atmospheric effects. Laboratory studies show that γHO<sub>2</sub> varies by orders of magnitude due to change in aerosol properties, especially those of aerosol soluble copper (Cu) and aerosol liquid water content (ALWC). In this study, we develop a state-of-the-art model to simulate both gas and aerosol phase chemistry. A novel parameterized equation of HO<sub>2</sub> considering change in RH and aerosol Cu is developed based on model optimization toward all available lab experiments. 1 / γ = 1 / α + (3 × <i>v</i>) / (4 × 10<sup>6</sup> × <i>R<sub>d</sub> H</i><sub>corr</sub> <i>RT</i> × (5.87 + 3.2 × ln(ALWC / [PM] + 0.067)) × [PM]<sup>−0.2</sup> × [Cu<sup>2+</sup>]<sup>0.65</sup>) According to the new equation, highly variable HO<sub>2</sub> uptake coefficients (median value ∼0.1) were diagnosed for North China Plain and the impact of HO<sub>2</sub> uptake on the ROx budget is assessed.</p>