Using a sample of A-share listed companies on the Shanghai and Shenzhen stock exchanges from 2009 to 2022, this study investigates the impact of transactional social relations formed through common customers on accounting information comparability. The findings reveal that the presence of common customers facilitates imitation learning of accounting policy choices among firms, indicating that transactional social relations significantly enhance accounting information comparability. Further analysis indicates that legitimacy pressures, and customer demand for comparable accounting information jointly motivate focal firms to imitate accounting policy choices. Additionally, focal firms tend to imitate the accounting policy choices of industry leaders and geographically adjacent firms through common customers. Heterogeneity analysis shows that the positive effect of transactional social relations on accounting information comparability exhibits substantially more pronounced effects when firms undergo CEO turnover, have a higher degree of business complexity, face higher environmental uncertainty, or operate in regions with stronger rule of law. The economic consequences test shows, the enhancing effect of transactional social relations on accounting information comparability not only strengthens the stability of customer relationships but also optimizes the composition of the customer base. This study not only enriches the research on imitation pathways in corporate accounting policy choices but also provides significant insights for regulatory authorities to enhance corporate information disclosure quality by leveraging customer relationships.