The capital cost is the total outflow of a firm's economic profit in order to obtain and use capital.In the industry-based economy era,financial capital is the main capital.But in the age of knowledge-based economy,human capital is the most important capital.Financial capital is the condition of creating value.The request of building human capital accounting is proposed in accounting theory.But in the financial theory,no research is about moving human capital cost into capital cost.So the content of capital cost is not consummate.In the paper,the content of capital cost and the financial theory is developed.