Facing the serious unemployment in China, there is a popular viewpoint in researchers and governments considering that developing service is able to expand employment and to reduce the rates of unemployment. According to the related data coming from World Band, this paper studies the relationships between employment proportion in service and gross employment, and between the employment proportion in service and the rates of unemployment by econometric methods. Based on the study, we draw the conclusions that there is a strong positive correlation between employment proportion in service and gross employment, and the positive correlation also exists between employment proportion in service and gross labor supply, between employment proportion in service and labor participation rates of women. These findings can explain such phenomenon in developed countries that rates of unemployment didn't decrease with increasing of employment proportion in service.