Using the MJO (MaddenJulian Oscillation) index data from 1979 to 2015 supplied by the Australian Bureau of Meteorology, the NCEP/NCAR global reanalysis data, and the typhoon data index from the Shanghai Typhoon Institute of the China Meteorological Administration, this paper analyzes the relationship between the different phases and intensities of MJO and the impact of tropical cyclones from July to October in Hainan. The results show that the tropical cyclone active and quiet periods affecting Hainan Island are related to the phases and intensities of MJO from July to October, but the corresponding MJO phases and intensities of tropical cyclone active and quiet periods are different in the period of July to August and the period of September to October. In July and August, when MJO is in strong phase (the third, sixth phase) or weak state (the fourth phase), it is beneficial for tropical cyclones to influence Hainan Province. When MJO is in first, second and eighth phases in strong state, it is not conducive to tropical cyclone’s influence in Hainan. In September and October, when MJO is in the seventh phase, it is favorable for tropical cyclones to affect Hainan Island. When MJO is in first and eighth phases, it is not conducive to tropical cyclones affecting Hainan Island. In July, August, September, and October, the circulation situations corresponding the MJO phase that is favorable/unfavorable to the activities of tropical cyclones, are basically the opposite.