The WRF model was used to simulate a mesoscale convective complex (MCC) weather process in Southwest China in June 2009.Combined with HYSPLIT Lagrangian trajectory analysis, the characteristics and mechanism of troposphere-to-stratosphere transport (TST) dominated by the MCC were discussed.The conclusions are as follows:(1) There are two source regions for particles near the tropopause in the MCC.In a short time (within 6 h), most of them come from the lower troposphere over the southwest region, guided by the low-level southwesterly.With the increase of time (accumulated to more than 12 h), the particles from the middle and upper troposphere over the north region gradually increase, which are guided by the airflow behind the northern upper trough.(2) The 24.2% of particles in the boundary layer below the MCC are transported to the stratosphere, which are also controlled by other two large-scale weather systems around them respectively.Most of the particles that finally enter the stratosphere are transported vertically and quickly into the tropopause by the MCC, and then move westward into the stratosphere under the influence of the peripheral circulation on the south side of the South Asian High.A small parts of the particles that finally enter the stratosphere firstly escape from the MCC, and then are transported to the northeast with the southwest airflow, encounter the mid-latitude frontal system, transport eastward over Japan and also enter the stratosphere through the joint action of slow frontal climb and fast westerly jet.