To improve the accuracy of convection weather forecast, one of the key issues is to find out the atmospheric vertical stability and wind shear. The mesoscale numerical model provides information on the atmospheric vertical stability and wind shear with high spatial and temporal resolution, and the reliability of the parameters derived from model output need to be well checked for the further application to the convection weather forecast. Using the radiosonde data of Beijing weather station, the convective parameters from mesoscale numerical model MM5 with a resolution of 3km run in Beijing Meteorological Bureau are carefully checked. The convective parameters are compared between the forecast results and the soundings. Results show that wind and temperature profiles produced by the model are useful to some extent,while when inversion or strong shift of wind direction occur, simulation results are much poorer. The forecast dew point profiles show very large errors, indicating the model gives a very poor water vapor distribution. The predicted deep layer vertical wind shear (from ground to 500hPa) shows good consistence with the radiosonde data, while the simulated CAPE is totally different from the observed value because of the errors in predicted temperature and dew point . The simulated CAPE value must be properly revised in order to diagnose the possible occurrence of the strong convective weather.