Since ancient times Macau has been an immigrant society where immigration and emigration of a large number of people have been closely related to the rise and decline of the city. A large number of mainland Chinese have moved to Macau ever since the adoption of an opening-up policy by mainland China in 1979. The arrival of these “new immigrants”has brought down the labor costs of Macau's traditional industries, resulting in a rapid industrial growth. However, these newcomers have also caused many social problems, including the deterioration of public order. In short, the new immigrants have had significant impact on Macau, both positive and negative. This article discusses the formation and special characteristics of these new immigrants as well as their influence on Macau.