Street labor market is spontaneously formed in urban streets. As an informal urban labor market, it has accumulated a large number of social problems and is regarded as an urban chaos, which affects the employment quality of migrant workers. Based on the field study of a typical street market case, this paper introduces the concept and method of service design into the study of urban informal labor markets. This paper analyzes the specific needs of market participants such as migrant workers and employers through user-centered and action-oriented research methods, proposes the comprehensive design of street labor market services, and discusses the sustainable development methods of informal labor market services. The research points out that although the street labor market is a spontaneous social phenomenon, its operation mechanism and the social relations of participants can make it become an innovative urban public service system. The introduction of service design thinking and social innovation methods into the solution of street labor markets can broaden the ideas for solving the flexible employment of migrant workers, and also provide a new reference for the innovation and development of urban public service systems.