Abstract: The best track data of tropical cyclones provided by the Joint Typhoon Warning Center (JWTC) of USA navy over the Western North Pacific including the South China Sea from 1945 to 2005 were employed to analyze the temporal-spatial variations of tropical cyclones with different intensities. Most tropical cyclones with different intensities occurred in the area from the northern part of the South China Sea to the eastern part of the Bashi Channel near 140°E or from 15°N to 25°N, and most severe typhoons and super typhoons occurred in the sea area from the eastern part of the Bashi Channel to about 140°E. The tropical cyclones in a weakening or steady state occupied a weaker majority in the area west of 123°E. The majority of tropical cyclones were in an intensifying or steady state in the area east of 123°E or south of 20°N, and in a weakening or steady state in the area north of 20°N. The average decaying rates for severe tropical storms, typhoons, severe typhoons, and super typhoons were all greater than the average growing rates, respectively, but the average decaying rate for tropical storms was smaller than the average growing rate. Generally speaking, the stronger the tropical cyclone, the faster the intensification (weakening). Compared with the other months in one year, the percentage of weak tropical cyclones was higher in June to August while in September to November the percentage of strong tropical cyclones was higher. There were the annual, interannual or interdecadal variations of the observation number(every 6-h) and frequency of tropical cyclones with different intensities. As far as long-term trend be concerned, the frequency and observation number of tropical storms showed a significantly linearly increase trend, but the mean intensity of tropical cyclones and the numbers of the tropical cyclones of other intensity categories did not exhibit any significantly linear increasing or decreasing tendency. In El Ni?o years, the number and ratio of super typhoons were significantly more, while the total number of tropical storms, severe tropical storms, typhoons and severe typhoons was significantly less, and the mean intensity of tropical cyclones was significantly stronger; however in La Ni?a years the opposite was true.