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In snow-icy road environment, the survey data indicate that the largest decrease in traffic flow run-ning characters occurs when snow and ice begin to accumulate on the road surface. Saturation flow is decreased by 16%, speed is decreased by 30%, and start-up lost time is increased by 27%. Based on the signal control theory of HCM and Webster, the character values of traffic flow in different urban road environments were inves-tigated, and the evolvement regularity of signal control parameters such as cycle, split, green time, offset,yellow time and red time in snow-icy road environment was analyzed. The impact factors and the changes in the scope of signal control parameters were achieved. Simulation results and practical application show that the sig-nal control plan of road environment without snow and ice will increase the vehicle delay, stop length and traffic congestion in snow-icy road environment. Thus, the traffic signal control system should address a suitable signal control plan based on different road environments.