To investigate the impact of the urbanization on the city meteorological conditions, the city group of the middle Liaoning was regarded as test area, a case of heavy pollution in winter was chosen and analyzed by means of the mesoscale numerical model (MM5). The results show that MM5 has a good performance to study the impact of the urbanization on the regional meteorological conditions. Furthermore, the impact of the urbanization development on the surface physical parameter makes the wind speed and specific humidity of surface layer decrease while makes the air temperature rise, meanwhile it makes the inversion intensify and deteriorate the local meteorology condition.