Over the past 20 years，the mass gaming in Macao has undergone a dramatic change，from being little to being significant，and to enjoying great expectation for future. This study demonstrates the chronic changes in the mass gaming in Macao through interviews with casino staff，investigations on visitors’ characteristics，facilities and service delivery，and job characteristics of the staff. Since the liberalization of the gaming industry，the mass gaming has been expanding at high speed，but the number of visitors mostly remains large and the income keeps stable. The visitors mostly came from Hong Kong in the past but mostly come from mainland China now. The numbers of family visitors and young visitors are increasing. Instead of focusing on gambling，the visitors mainly seek for entertainment and multiple purposes now. Besides，the gaming facilities are developing in large scale and smart capability. The dealers no longer neglect customers but carefully cater them. Service quality，supported facilities，non-gaming projects and membership promotion are the key for fighting against rivals. In addition，in spite that the working environment has become healthier and more humanized，the posts in mass gaming has become less attractive due to relatively lower salary，fewer promotion opportunities and increasing working pressure. Looking into the future，the mass gaming still has a large potential，which will go ahead towards visitors being mainly occupied by tourists，facilities becoming smarter，service and non-gaming developing with intense competition，and working environment being healthier and more humanized.