This paper aims to provide new evidence on the relationship between green investment and firm performance through micro-level data. Data of energy listed firms in China from 2008 to 2017 are used here to explore this relationship. The research results show that green investment has a significant and positive correlation with financial performance, that is, increasing green investment helps improve financial performance. In the third year after investment in energy conservation and emission reduction, financial performance has been significantly improved. Additionally, environmental tax, government subsidies, and technological innovation have different positive moderating effects on green investment in promoting financial performance, and this result is more obvious in the long-term performance. Lastly, this paper finds that green investment helps reduce environmental violations and promote environmental performance, and environmental performance can strengthen the impact of green investment in improving the long-term performance of firms. This conclusion implies that firms should take environmental investment as its long-term strategy.