Background: This study aimed to investigate the pulmonary ventilation function (PVF) according to different types of rib fractures and pain levels.Methods: This was a retrospective study of patients with thoracic trauma admitted to our ward from May 1, 2015, to February 1, 2017. Vital capacity (VC), forced expiratory volume in 1 s (FEV1), and peak expiratory flow (PEF) were measured on admission. A numerical rating scale (NRS) was used for pain assessment.Results: A total of 118 (85 males and 33 females) were included. The location of rib fractures did not affect the PVF. When the number of rib fractures was ≥ 5, the PVF was lower than in those with ≤ 4 fractures (VC: 0.40 vs. 0.47, P = 0.009; FEV1: 0.37 vs. 0.44, P = 0.012; PEF: 0.17 vs. 0.20, P = 0.031). There were no difference in PVF values between multiple and non-multiple rib fractures (VC: 0.41 vs. 0.43, P = 0.202; FEV1: 0.37 vs. 0.39, P = 0.692; PEF: 0.18 vs. 0.18, P = 0.684). When there were ≥ 5 breakpoints, the PVF parameters were lower than those with ≤ 4 breakpoints (VC: 0.40 vs. 0.50, P = 0.030; FEV1: 0.37 vs. 0.45, P = 0.022; PEF: 0.18 vs. 0.20, P = 0.013). When the NRS ≥ 7, the PVF values were lower than for those with NRS ≤ 6 (VC: 0.41 vs. 0.50, P = 0.003; FEV1: 0.37 vs. 0.47, P = 0.040; PEF: 0.18 vs. 0.20, P = 0.027).Conclusions: When the total number of fractured ribs is ≥ 5, there are ≥ 5 breakpoints, or NRS is ≥ 7, the VC, FEV1, and PEF are more affected.Trial registration: The trial was conducted in accordance with the Declaration of Helsinki (as revised in 2013). The study was approved by the Ethics Committee of Shanghai Jiao Tong University Affiliated Sixth People’s Hospital and individual consent for this retrospectively registered analysis was waived.