Abstract: This study uses the Shangdianzi national background station in Beijing to represent the background area in North China, and adopts the Ozone Source Appointment Technology (OSAT) method of the CAMx model to analyze the ozone source contribution in North China background areas from June 25 to July 31, 2019. A simulation study of O₃ concentration was conducted to quantify the contribution of different source components and tagging regions, aiming to deeply analyze the source composition of ground-level O₃ concentration in the background area of North China. The components that contribute to the ground O₃ concentration in this region, from high to low, were boundary transport (61.8%), source transport (31.8%), background concentration (3.3%), and local generation (3.1%). The main source tagging regions from high to low were were Hebei province (5.70%), Inner Mongolia autonomous region (5.43%), and Shandong province (4.48%). The source categories were civil source (15.35%), agricultural source (10.72%), transportation source (7.21%), and industrial source (1.62%), and the main precursors were NO_x (29.6%) and VOCs (5.3%). The ground ozone concentration in North China background area is mainly contributed by boundary transport and source transport, which further validates the rationality for Shangdianzi station as an atmospheric background station.