Abstract: On 12 July 2002,a MCS initialed in a cold vortex over Northeastern China brought torrential rain over Liaoning province. This MCS was simulated successfully by Penstate/NCAR mesoscale model (MM5). The synoptic environment to MCS generation were provided by baroclinic disturbances and favorable potential instable layer of south front zone located on the northeastern cold vortex. In the development phase of MCS, meso-scale strong updraft produced by low-level meso-scale conv ergence which was caused by instable energy accumulation and meso-scale energy frontal zone in low layer and meso-scale cyclone circulation broke stable middl e layer, and incline updraft gradually grow upright. In the mature phase of MCC,surface pressure field presented strong thunderstorm high and weak leading low and wake low. The discontinuity line between boundary layer cold dome correspon ding thunderstorm high and southern warm wet flow strengthen convergence lifting . Combination of leading low and 800-700 hPa warm core low, which is disturbance of low pressure caused by surface convergence and updraft pump and potential he at warming, play important role to convective system maintaining and movement. After meso-high formed, the meso-scale convergence line which was produced by sinking outer flow and environment flow is the main flow convergence source of boundary layer cold dome affect the distribution of meso-scale temperature field and humidity field. The strong temperature grads and humidity grads are corresp onding strong meso-scale wet baroclinic effects. Cold dome changed the atmosphere layer condition and this not only affect itself move but also affect other storm cell move and develop.