To solve the uncertainty problems in traffic assignment,this paper established a method of quantifying the uncertainty in traffic assignment model based on Wardrop user equilibrium principle and Beckman traffic assignment model.The model uses the upper and lower limits of OD estimation results under different confidence levels as inputs,and subsequently uses the Frank-Wolf algorithm to solve the model to obtain link traffic flow intervals under different confidence levels to quantify uncertainty in traffic assignment.A case study utilizing a regional road network in Nanjing is performed,and the results were evaluated using the width flow ratio R and the kickoff percentage (KP) as the performance measures.The evaluation results show that the proposed method can effectively compute the confidence intervals of the road link flow,thereby quantifying the uncertainty in traffic assignment.