Abstract:The movement track, vibration-resistant pressure, circulation background, characteristics of air temperature and humidity fields, and of dynamic fields of the tropical cyclones Mala over the Bay of Bengal originated in 2006 springtime are analyzed based on the real-time observation data and NCEP 6- h reanalysis data with resolution 1°×1°. The results show that the Mala was originated and strengthened in the convergent area between the Arabia subtropical high and the western north Pacific subtropical high, and moving along south-west or south current over west side of the western north Pacific subtropical high. Compared to the differences made by humidity and temperature, humidity has a more obvious effect on the Mala during its origination, mature and regression. Except Malas same normal dynamic field features as typhoon, it has an alternated structure of convergence and divergence from low level level to high level of divergence field nearby the center. The phenomenon shows that the pumping in the Mala was processed by relaying. Under the co-effect of the Malas inner energy caused by low pressure, vapour and cold air, severe rainfalls in Yunnan Province were mainly caused by tough air upward movement and mesoscale convergence line in the warm and cold confluent area.