Based on conventional data, automatic weather stations observations, Doppler weather radar products, satellite image and NCEP/NCAR daily 6 h reanalysis data, the environmental conditions and storm features of a regional thunderstorm gale on July 9th 2017 were analyzed. The results show that the thunderstorm gale occourred under the influence of upper northwestern flow, the lower vertical wind shear, high temperature lapse rate and the accumulation of abundant energy in the lower layer were favorable for its occurrence. Ground cold front, dry intrusion and mesoscale convergence line were triggering mechanism. The organized band was composed by scattered convective clouds in front of the cold front along the surface mesoscale convergence line. At the first and the second stage, the gale with wind force scale greater than 10 occured at the mature stage of thunderstorm clouds, it was mesocyclone type in the first period, the mesocyclone appeared  first in the middle layer, and then developed to the lower and higher layers, the thunderstorms broke out when the bottom of the mesocyclone dropped to 2.2 km. At the second stage, it was mainly the gale type caused by the strong inflow behind the thunderstorm cloud at low altitude ( 1.0 km). The gale with wind force scale greater than 10 at the third stage appeared in the extinction period of thunderstorm clouds, which was formed by strong outflow in front of thunderstorm clouds.