Abstract: The "Two Mountains" theory,put forward by President Xi Jinping,means that good environment is the mostvaluable asset.Essentially it is to reveal the relationship between economic development and environmental protection,which can be used to effectively explain the choice,abandonment and persistence of human beings in the development of China’s economy and even the world economy.At present,China can practice the "Two Mountains" theory by taking "ecological priority" path in the forbidden development zones,"green development" path in the key development zones,and "ecological priority,green development" path in the restricted and optimized development zones.In the practice of classification,there is an urgent need to carry out policy guidance through measures such as implementing differentiated financial investment policies,innovating indirect financial input methods,increasing the considerations for determining environmental taxes,and perfecting the green credit incentive mechanism.Measures should be taken to guarantee the rule of law,such as the construction of the model of "collaborative procedure" of regional collaborative legislation,the checks and balances of the "functions and responsibilities" of the river head,the aggregate creation of the "cross-line responsibility" of the ecological protection red line,the clear procedure of inspectors' "intensified accountability" of environmental protection,the index setting of "characteristic evaluation" of environmental credit,and so on.

Key words: "Two Mountains" Theory, ecological priority, green development, ecological civilization