Shadow price refers to a price that is different from the current market price in national economic evaluation and can reflect its actual value.

Shadow price, also known as "optimal price", "calculated price" and "predicted price", was first put forward by the Dutch economist Jan Dingbergen in the late 1930s. It was calculated by using the mathematical method of linear programming and reflected the optimal allocation of social resources. He believes that shadow price is "a reasonable valuation of labor, capital and commodities imported from scarce resources". In 1954, he defined shadow price as "the intrinsic or real price of production factors or products in the sense of balanced price". Samuelson further developed that shadow price is a mathematical expression, which reflects the price when resources are used optimally. The United Nations defines the shadow price as "the opportunity cost of an input (such as capital, labor and foreign exchange) or the loss caused by the reduction of its supply by one unit to the whole economy".

Shadow price is an important parameter of economic evaluation of investment projects, which refers to the price that can reflect social labor consumption, resource scarcity and final product demand when the society is in the optimal state. Shadow price is a measure of the real value of goods by society, and it will only appear under perfect market conditions. But this perfect market condition does not exist, so the ready-made shadow price does not exist. Only by adjusting the current price can we get its approximate value.