This paper provides a contribution to the issue of signal control in a sensitive junction under disaster conditions. A signal control parameters optimization model is presented in order to prevent the spillback of queue in a short approaching link. Starting from an equilibrium equation, store-and-forward method based, this paper depicts the vehicular arrival and departure in a link. In addition, a minimum problem is presented aiming at that the evacuation demand approaching the sensitive junction can depart safely，efficiently with equal opportunities. Then a solution method, based on a improved FW, is proposed. At last, a simulate case via the simulation software – VISSIM is described. The results read that not only the model can prevent the spillback of sensitive phase but also enhance the entire throughout of the junction.