Based on the definition of rapidly intensified offshore tropical cyclone (RIO-TC), statistics of the characteristics is made for the 46 RIO-TC cases close to South China coast from 1949 to 2004, and some valuable facts are found. The general circulation of the cases is studied statistically and found the RIO-TCs occur in three patterns of high-east-low-west, high-north-low-south and weak environmental flow, and the inducing systems are mainly southwest monsoon, cross-equatorial flow, easterly wave, weak cold-air and westerly trough under the different patterns.