The time that information provided, determined the usefulness of information and timely disclosure of information, protect investor about poor news. That may be change firm future prospects completely. In this research we studied the determinant of the timeliness of financial reporting in Tehran stock exchange.We applied Quasi-Empirical approach and descriptive-correlation methods to test there search hypotheses. Also we used multivariate regression models about this. The results of this study show that in this period we have a negative relationship among between firm’s size, audit opinion, management change, and percentage of institutional ownership with Audit delay. Also, we have been finding out positive relationship between internal auditor existence, number of shareholders, and non ordinary items with Audit delay. Indeed this research provided evidence about corporate governance power for explaining Audit delay and timeliness of reporting too.