Objective To discuss the influencing factors of hypoxemia during one‑lung ventilation (OLV) by logistic regression model and Chi‑squared automatic interaction detector (CHAID) decision tree model and their relationship. Methods A total of 142 patients who underwent OLV thoracic surgery in the Second Hospital of Shanxi Medical University from October 2021 to June 2022 were selected. Their gender, age, body mass index (BMI), hemoglobin (Hb) level, smoking history, operation side (left/right), forced expiratory volume in first second (FEV1), percentage of forced expiratory volume in first second to forced vital capacity ratio (FEV1/FVC), arterial partial pressure of oxygen (PaO2) during spontaneous ventilation, PaO2 in the lateral position for 10 min, and the difference in end‑expiratory partial pressure of carbon dioxide (d‑PETCO2) between the dependent lung and the non‑dependent lung in the lateral position for 10 min were collected. According to the occurrence of hypoxemia during OLV, the patients were divided into two groups: a hypoxemia group (n=23) and a non‑hypoxemia group (n=119). Univariate correlation analysis was performed using the variable data of the two groups, where those with P<0.05 were used to construct a logistic regression model and a CHAID decision tree model, in order to explore the influencing factors of hypoxemia during OLV in patients undergoing thoracic surgery. Results Among 142 patients undergoing OLV thoracic surgery, the incidence of hypoxemia was 16.20％ (23/142). Univariate correlation analysis indicated that BMI, operation side (left/right), FEV1/FVC, and PaO2 and d‑PETCO2 values in the lateral position for 10 min were related to hypoxemia. Furthermore, logistic regression analysis showed that d‑PETCO2 in the lateral position for 10 min [odds ratio (OR) 0.52, (95％ confidence interval (CI) 0.36, 0.75), P<0.001], FEV1/FVC [OR 0.82, (95％CI 0.70, 0.97), P=0.016], and PaO2 in the lateral position for 10 min [OR 0.98, (95％CI 0.96, 1.00), P=0.018] had statistical effect on the occurrence of hypoxemia. The CHAID decision tree suggested that d‑PETCO2 in the lateral position for 10 min, FEV1/FVC and BMI were the influencing factors for hypoxemia. The first layer of the tree was divided according to d‑PETCO2 value in the lateral position for 10 min, and the second layer of the tree was divided according to BMI and FEV1/FVC ratio for patients whose d‑PETCO2 was between (1, 4] or >4. There were interactions between d‑PETCO2 in the lateral position for 10 min and FEV1/FVC, and d‑PETCO2 in the lateral position for 10 min and BMI, respectively. Conclusions d‑PETCO2 in the lateral position for 10 min and FEV1/FVC have important predictive value for the occurrence of hypoxemia during OLV, and there is a certain relationship between them. The logistic regression model and the CHAID decision tree model are mutually verified, which can efficiently identify hypoxemia high‑risk populations during OLV.