There are three key problems in Hainan Island, i. e. Devonian sediments, Caledonian movement and Caledonian granite. In the process of 1: 50, 000 regional geological surveys of the Changjiang Sheet and Bangxi Sheet, some important advances have been made in these problems. (1) According to the first discovery of the coral Cvxtophrentis kalaohoensis Yu and the study of cyclic stratigraphy , it is suggested that the middle and lower parts of the Nanhao Formation might belong to Middle-Late Devonian sediments in the Jixing-Jishi area,Changjiang County. (2)The Caledonian granite has been first outlined in the Baomeiling area .which is 369-410 Ma in age. (3) According to the regional angular unconformity and metamorphic and deformational characteristics, the Caledonian movement has been determined to be an important tectonic event in the crustal evolution of Hainan Island and may be compared with the Late Caledonian movement of South China.