Education, including training and formal schooling, can play an important role in increasing human capital. It is impossible to know all these desirable qualities when recruiting employees. Therefore, the employer is faced with the problem of choice: because it is difficult to accurately predict the future performance of job seekers, he tries to use education level as a review tool to distinguish the ability, achievement motivation and possible family roots of new employees, that is, education level is used to measure personal quality rather than cognitive skills; On-the-job training needs cognitive ability to a great extent. Therefore, employers essentially choose job seekers according to their employees' training potential. Therefore, the contribution of education to economic growth only provides employers with a choice tool.

However, the expansion of education is unlikely to have much impact on the income gap, because the increase of college graduates will only raise the employment standard. As the human capital theory says:

According to the examination of academic qualifications, the employer sent a "signal" to some employees to maximize the probability of being selected, that is, to obtain an education diploma. This signal stimulus is actually transmitted through the private rate of return on education investment.

The influence of human capital on education;

Human capital is a form of capital which is opposite to material capital. Reflected in people, used to provide future income; Education is the most important way to form human capital, and education plays a continuous role in economic growth through the formation of human capital.

1935, American economist J.R. Walsh published "The View of Human Capital", and put forward the concept of human capital for the first time. Starting with the comparison of the present value of personal education cost and income, he tried to demonstrate that education expenditure conforms to the principle of general investment. 1958, American economist T.W. Schultz published the article "Emerging Economic Phenomenon and its Relationship with Higher Education", and put forward a complete concept of human capital. Later, he estimated the cost value of human capital in books and papers such as Capital Formed by Education, Economic Value of Education, and Human Capital Investment: the Role of Education and Research, and speculated that school education had an impact on the economy. Under his influence, the concept of human capital has become a hot research field, and Schultz is also known as the father of the concept of human capital.

The human capital theory formed by human capital research studies the relationship between human capital investment and income. According to the theory of human capital, a comprehensive concept of capital should include material capital and human capital. Capital embodied in the form of machines, factories, equipment and other physical objects is material capital; The capital embodied in the form of knowledge, skills and physical strength is human capital. Human capital is formed through human investment, which includes education expenditure, medical expenditure, domestic labor mobility expenditure and immigration expenditure. Human capital is the present value of past investment in people's abilities (including physical strength and intelligence). It is a kind of capital with high rate of return, and its function is far greater than that of material capital. It is the main source of economic growth and the main way to narrow the income gap and solve the poverty problem. The growth rate of human capital has exceeded the growth rate of material capital and has become the most important development factor of modern industry and agriculture. The focus of capital accumulation should shift from material capital to human capital.

The concept and theory of human capital have a great influence on development economics and growth economics, and become one of the theoretical foundations of modern educational economics.