In order to quantify the monetary value of ecosystem services for ‘Lucid Waters and Lush Mountains are Invaluable Assets’ Practice Bases (‘Two Mountains’ bases) and evaluate transformation approach from ‘lucid waters and lush mountains’ to ‘invaluable assets’, this study developed a framework of gross ecosystem product (GEP) accounting which is suitable for ‘Two Mountains’ bases based on recent advances in ecosystem value accounting. The framework of GEP included the value of ecological products provision, ecosystem regulating services, and ecosystem cultural services. At the same time, the total value of ecological products provision and ecosystem cultural services was used to evaluate the transformation from ‘lucid waters and lush mountains’ to ‘invaluable assets’. Taking Ninghai County in Zhejiang province as an example, this paper evaluated its GEP from 2011 to 2018. The results showed that the GEP of Ninghai County increased by 47.78% from 2011 to 2018.The GEP in 2018 was 125.90 billion Yuan, of which the value of ecosystem regulating services was the highest, accounting for 53.26%. The GEP was 1.09 times higher than the GDP. In 2018, the transformation value was 58.84 billion Yuan, an increase of 139%. Tourism was the dominate driver of the increase. The changes in GEP from 2011 to 2018 were the results of the construction of ‘forest Ninghai’, the development of ecological tourism, and the implementation of ecological compensation. The findings of the study show that this GEP accounting system can be applied to account, assess and monitor the development performance of ‘Two Mountains’ bases.