In this paper,we have analyzed the arrival rate of the passengers and the energy-cost of the elevator traffic during up-peak. We proposed the dynamic transition point of 4 elevators in order to reduce energy consumption using the nonlinear-map model. The energy-cost depends on the arrival rate and the round-trip time directly, so we give the relationship of the changes of the arrival rate and round-trip time distribution functions. Due to the distribution of the arrival rate depends strongly on the number of passengers arriving at the lobby. The arrival rate of the passengers is divided into three stages. During the lower-peak stages, according to the round-trip time functions, the cars varies from 1 to 4 at the transition point. The simulation shows that the energy consumption of the algrithm proposed in this paper is lower than that of the average arrival rate. This method can also be applied in the other traffic modes.