Objective To explore the difference in positioning accuracy between deep-inspiration breath-hold (DIBH) and freebreathing under cone beam computed tomography (CBCT) image guidance in proton radiotherapy for thoracic and abdominal tumors, and to provide a basis for optimizing respiratory management strategies in clinical practice. Method A retrospective analysis was conducted on 50 patients with thoracic and abdominal tumors who received proton radiotherapy in Hefei Ion Medical Center from January 2022 to April 2025. They were divided into a free breathing group (n＝25) and an DIBH group (n＝25). All patients received CBCT guidance during the first 5 radiotherapy sessions, and the positioning errors in the X, Y, and Z directions, three-dimensional vector errors (TVE), and angle deviations were recorded. At the same time, the adjustment amplitude of the treatment bed, correction time, repositioning incidence, and the impact of weight changes were compared. Results DIBH group had significantly lower Y-axis error and three-dimensional vector error than the free breathing group (P＜0.05), with smaller Pitch angle error as well (P＜0.05). The correction time was shorter in the DIBH group (P＜0.05), and the repositioning rate was lower (P＜0.05). There was no significant difference in the influence of body weight fluctuation on fixation and respiratory management between the two groups (P＞0.05). Conclusion Under CBCT image guidance, the DIBH method can significantly improve the positioning accuracy and efficiency of proton radiotherapy for thoracic and abdominal tumors compared to free-breathing, reduce the risk of repositioning.