This study investigates the relation between voluntarily disclose companies’ monthly earnings and earnings timeliness. Further testing month earnings disclosure frequency affect earnings timeliness. The relationship between earnings and stock price have been many scholars discussed problems, in the past studies have confirmed that earnings has company's price information content. Therefore, this study uses the Taiwan Economic Journal (TEJ) database, reference Basu (1997) model, using the earnings and stock price reverse regression testing the relation between voluntarily disclose companies’ monthly earnings and earnings timeliness. Empirical results show that voluntarily disclose companies’ monthly earnings and earnings timeliness have positive correlation. when the company disclosed month earnings information, the speed of response bad news was faster. This study discusses the relation between month earnings disclosure frequency and earnings timeliness. The results show the Disclosure month earnings more frequently, will be more quickly response the bad news.