To explore the mandatory lane-changing (MLC) behavior of vehicles in work zones on freeways and factors which influence vehicles' MLC behavior, semi-parametric method is used to establish the multiplicative hazard model of mandatory lane-changing duration. The traffic data on the duration of the lane-changing and factors of the vehicles in freeway maintenance construction area were collected by an Unmanned Aerial Vehicle, and lane-changing data has been analyzed by Cox regression analysis. The results show that nearly 77% of the lane-changing duration is in 10 s. The effect of different vehicle types on the duration of mandatory lane-changing is not significant. The cumulative survival rate of off-peak period was significantly lower than that of peak period and transition period, and the cumulative survival rate of the peak period is the highest. The influence of lane changing vehicle types and traffic time periods on MLC for work zones on freeways can be conducted effectively using the survival model proposed. The model proposed and results from analysis can provide a theoretical basis for traffic management and control of work zones, and the modeling and simulation of freeway lane-changing behavior in high-speed and dynamic traffic environment.