Abstract: A computational method was developed to predict the effects of airframe icing on aircraft flight dynamic characteristics according to atmospheric conditions, aircraft characteristics and flight conditions. Ice accretion scaling was performed by means of heat-transfer balance analysis, and aerodynamic model of iced aircraft was built by means of stepwise linear regression, the aerodynamic parameters due to ice accretion were computed by this model. The agreement of the computation results with the flight data indicates this method could be used to estimate the aerodynamic parameters at the analyses of longitudinal stability and handling quality. The penalties of aircraft longitudinal stability and control due to ice accretion on different region were investigated using this method. The results of computation demonstrate that the severe degradation of aircraft aerodynamic performance due to ice accretion may affect longitudinal stability and handling quality significantly, and endanger the flight safety.