The paper points out that Hainan culture is a kind of frontier pioneering culture, and focuses on its areal diffusion and cultural integration. Frontier pioneering culture is a new form of culture which springs up in pace with the exploitation of frontier areas through joint efforts of dismissed government officials and garrison troops historically and by means of land reclamation in modern times. There are differences between Hainan Island and the mainland in the course of cultural diffusion. In mainland, culture is diffused along the rivers or the plains whereas in Hainan Island altitude is the most important factor that influences the diffusion of culture. Because of cultural dissemination and diffusion, different cultures assimilate, blend or even merge into an organic one, which were called cultural integration or cultural synthesis. The formation of Hainan culture resulted in the integration of various kinds of frontier pioneering cultures in Hainan Island in the long span of history. In other words, Hainan culture is the synthetic outcome of the complicated integration process of national cultures of Han, Miao and Hui nationalities and modern cultures, such as the cultures of overseas Chinese, culture of land reclamation and cultivation, the western cultures based on the background culture of Li nationality. This is the new form of Island culture that developed in Hainan’s environment.