Ecosystem assets refer to ecosystems that can bring benefits to people within specific temporal-spatial ranges and under given technological-economic conditions, including forests, grasslands, wetlands, farmland, etc. Ecosystem assets valuation can facilitate market-oriented transactions of ecosystem assets and promotes synergistic development of economy and ecosystems. The SEEA EA recommends using the net present value (NPV) method to assess ecosystem assets value, which first forecasts the value of ecosystem service flows actually provided to humans each year in the future, then discounts them to the accounting period and aggregates them. However, most studies assume constant future service flows without conducting forecasts when valuing assets. Furthermore, the SEEA EA emphasizes the need to forecast ecosystem service flows actually provided to humans. However, due to accessibility constraints between supply and demand sides and the absence of demand-side beneficiaries, there exists a discrepancy between ecosystem services potentially supplied and actually used by humans, which means the potential supply of ecosystem services does not equate to actual use of ecosystem services. Potential supply refers to an ecosystem's capacity to deliver ecosystem services under current ecosystem conditions, management practices, and utilization patterns, without compromising the maximum production or utilization levels of the same or other services in the future. Actual use denotes the ecosystem services actually used by humans and socio-economic systems within specific temporal-spatial boundaries. Although significant differences exist between potential supply and actual use, existing studies often conflate their measurement indicators, leading to inaccuracies in ecosystem assets valuation. To ensure accurate valuation of ecosystem assets, it is essential to clarify the accounting indicators for potential supply and actual use. Additionally, as ecosystem area, conditions, and management constrain service supply capacity, potential supply should serve as the threshold for actual use during valuation. Therefore, this study takes Hechi City as a case study, assessing both potential supply and actual use, establishing potential supply as the threshold for actual use, forecasting future flows of actual use, and subsequently applying the NPV method to value ecosystem assets. Key findings include: (1) In 2020, the total actual use value reached CNY 212.912 billion, the total potential supply value in 2020 amounted to CNY 633.623 billion; (2) Using 2020 as the baseline accounting period, Hechi City's ecosystem assets value was estimated at CNY 13.61 trillion, with Huanjiang County and Yizhou District showing the highest values at CNY 1.82 trillion and CNY 1.64 trillion respectively; (3) The unit area value of ecosystem assets in Hechi City reached CNY 406 million/km2, with Tian'e County achieving the highest unit area value of CNY 472 million/km2; (4) Integrating potential supply and actual use can reduce methodological biases, avoid issues arising from conflated definitions or oversight of potential supply, and enhance the accuracy of ecosystem assets valuation.