The so-called length of service refers to the working hours with wage income as the main source or all sources since the establishment of labor relations between employees and units. The only legal significance to the calculation of social insurance benefits is continuous service and service. Length of service refers to the working hours of employees whose income is the whole or main source of their lives. The length of service marks the length of employees' working hours, and also reflects employees' contribution to society and enterprises and their level of knowledge, experience and technical proficiency.