The origin of labor market segmentation theory can be traced back to John Mill and Keynes, who openly opposed Adam Smith's theory that the labor market was competitive and tended to think that the labor market was non-competitive. In 1960s and 1970s, the theory of labor market segmentation challenged the theory of labor market based on neoclassical economics, and different academic branches appeared, such as the theory of professional competition based on incomplete and uncertain information, the radical theory based on historical and institutional analysis, and the dual structure theory. The differences between these theories are mainly manifested in the differences in observation points, division methods and research methods, among which the dual structure theory is the most cited and becomes the representative of the labor market division theory. The dual structure theory divides the labor market into primary market and secondary market. This distinction was first put forward by Piol, a neostructuralist sociologist. The primary market has the characteristics of high salary, good working conditions, stable employment, good security, standardized management process and many promotion opportunities. The secondary market has low wages, poor working conditions, unstable employment, rude management and no promotion opportunities. The positions in the primary market are mainly composed of the internal labor market. The determination of wages and the allocation of labor resources are regulated by rules such as management system, and market forces basically do not work. The measures to solve the imbalance between supply and demand in the internal labor market mainly include recruitment, training, job redesign, subcontracting and output adjustment. Most of the employees in the secondary market are poor. Although the dual structure theory occupies a dominant position in the labor market, there are still two other different viewpoints. First, the labor market consists of multiple regions; Another view is that the labor market is a continuous work chain, and the wages on the "chain" vary greatly, but there is no clear area. Compared with other factor markets, the labor market is obviously uncompetitive. The theory of labor market segmentation in western countries explains this non-competitiveness with a new paradigm different from the traditional labor market theory. The theory holds that the traditional labor market theory can't explain the widening income gap of workers and all kinds of discrimination in the labor market, while the labor market segmentation theory emphasizes the segmentation attribute of the labor market and the important influence of institutional and social factors on labor remuneration and employment, so it has strong practical explanation ability. The main performance of labor market segmentation is that the labor market can be divided into primary and secondary labor markets and internal and external labor markets.