In this paper, the characters of mesoscale structurs near the trough line are analysed based on the wind data of Doppler weather radar.It is shown that there are mesoscale divergence and convergence regions exis-ting near the trough line,thus causing the uneven distribution of precipi-tation. A cold advection occurs is in the boundary layer near to the ground while a warm advection forming at the level between 2.5km and 5.0km. The vertical wind shear appears at the 2.0-2.5km high level and the weak updraft at 2.7km high level. The precipitation area moves northeastward, due to the influence of the mesoscale circulation.