Comparability is one of the qualitative characteristics of financial information that increases its usefulness and allows users to identify similarities and differences in the financial performance of companies. The present study examines the impact of the CEO's tenure on the ability to compare financial statements with an emphasis on auditor size. This research is applied in terms of purpose and in terms of methodology, correlation is a type of causal (post-event) research. All companies listed on the Tehran Stock Exchange have been selected as the statistical population of the study. Using the systematic elimination method, 123 companies were selected and surveyed over a period of 6 years between 1392 and 1397. The method used to collect information is library and multiple linear regression has been used to test the hypotheses. Stata version 15 software was used to perform the tests and estimate the models. The results of the research show that the tenure of the CEO has a significant effect on the ability to compare financial statements. The size of the auditor reinforces the direct impact of the CEO's tenure on the ability to compare statements.