This study aimed to investigate the relationship between corporate governance and financial ratio with the performance of companies listed on the stock exchange of Thailand with an excellent score. The data were collected from annual registration statement (Form 56-1) of 191 companies from 2016 to 2020. Descriptive statistics such as mean percentage standard deviation and Inferential statistics such as Pearson’s Correlation Coefficient and Multiple Regression Analysis were used to examine the relationship. The results showed that 1) Corporate Governance namely Board size the ratio of independent director and Managerial Ownership positively corelated with firm performance. 2) Leverage Ratios (Financial Ratio) namely Debt to asset ratio and Debt to equity ratio negatively corelated with firm performance but Interest coverage ratio positively corelated with performance

This research aimed to study earning quality sustainability factors (ESG) and the relationship between earning quality and sustainability factors of the 59 companies listed in the sustainability index (SET THSI INDEX). The data was collected from the financial statements annual reports sustainability report and the data entry forms (Form 56-1) from 2015 to 2019. Descriptive statistics and inferential statistics were used in the data analysis including correlation analysis and multiple regression analysis The results of the study showed that most of the companies listed in the SET THSI Index had higher earning quality than the index average. The sustainability factor that has the greatest influence on earning quality is good governance. When the relationship between earning quality and sustainability factors (ESG) was analyzed it was found that there was a statistically significant correlation between environmental disclosures and good governance namely the number of the Board of Directors shareholding by Thai juristic person at the levels 0.01 and 0.05. There was a statistically significant opposite correlation between the disclosure of social responsibility information including anti-corruption aspect human rights aspect and responsibility to consumer aspect; and good governance including the proportion of shares held by family companies at levels 0.01 and 0.05.