Abstract: 55-year data sets are used to study the statistical characteristics in intensity change of tropical cyclone (TC) over the Western North Pacific. According to the mathematical meaning of average value and standard deviation, the rapid deepening, slow deepening, stable, slow filling and rapid filling of TC intensity are defined and the statistical characteristics, such as inter-decadal variation, inter-annual variation, inter-monthly variation, daily variation and regional distribution, etc. are analyzed. Main results are as follows: (1) The range of TC intensity change is smaller before the 1960's. (2) The range of TC intensity change in August is the smallest among summer and autumn months. TC deepens the easiest at 14:00 (L.T.), fastest at 08:00 and slowest at 02:00. TC fills the easiest at 20:00, fastest at 02:00 and slowest at 20:00. (3) The region where TC deepens most frequently is the northern South China Sea and east of Philippines. The region where TC fills most frequently is around the islands and continent. (4) The rapid deepening TC seldom occurs over mid-and high-latitude area (north of 30°N) and low-latitude area, sometimes occurs around the islands and continent. Basically there is no slow deepening TC over mid-and high-latitude area (north of 30°N and west of 125°E), in offshore Chinese waters. The slow filling and rapid filling TCs usually occur offshore China, west of 125°E, but seldom over low-latitude area (0-5°N).