Background <p>Behavioural speech therapy (BST) is a non-drug treatment for chronic cough. This study aimed to evaluate the impact of behavioural speech therapy based on the transtheoretical model on chronic cough and quality of life in lung cancer patients undergoing thoracoscopic surgery.</p> Methods <p>In this prospective randomized controlled trial, patients were randomly assigned 1:1 to receive either the BST intervention or standard care every 2&#xa0;weeks for 3&#xa0;months after surgery. The primary outcomes included the prevalence and severity of chronic cough; the secondary outcomes included cough-related quality of life, anxiety and depression. Data were collected at admission (T0), 1&#xa0;month post-surgery (T1), and 3&#xa0;months post-surgery (T2). A mixed-effects model was used to assess changes across time points and outcomes. The study was registered with the Chinese Clinical Trial Registration (ChiCTR2400084313; May 14, 2024).</p> Results <p>Between July and September 2024, we enrolled 112 patients for baseline assessment (57 patients in the intervention group and 55 patients in the control group). The prevalence of chronic cough was significantly lower in the intervention group than in the control group (21.1% vs. 43.6%, adjusted RR = 0.35, 95% CI: 0.19–0.64; <i>P</i> &lt; 0.05). The mean difference in cough score was 4.11 (95% CI: -5.33 to -2.89; <i>P</i> &lt; 0.001) lower in the BST group than in the control group from baseline to T2. The cough-related health scores of the intervention group were better than those of the control group in all dimensions after 1&#xa0;month and 3&#xa0;months. The mean differences in anxiety and depression in the BST group were greater than those in the control group from baseline to T2.</p> Conclusions <p>BST effectively decreases the prevalence of chronic cough, alleviates cough symptoms and improves quality of life.</p>