This article presents an energy management approach for the hybrid energy storage system in an electric bus at different temperatures. An electric bus equipped with a semi-active hybrid energy storage system is considered as the research object. According to the urban climatic characteristics of the vehicle running, the convex optimization approach considering temperature factors is proposed. The purpose of this study is to minimize the energy loss and maximize the discharge and charge depth of the super capacitor. Simulation results show that the comprehensive energy efficiency of the proposed method is 83.31% and the comprehensive energy efficiency is improved by 2.42% at 25°C, which is compared with the rule-based power allocation method based on urban driving cycle in Harbin, China. When the ambient temperature is 25°C, the comprehensive energy efficiency of the proposed method is 81.03%. This result is improved by 1.45% and the battery power variance at 25°C is reduced by 20.11% compared with the rule-based power allocation method. Therefore, the proposed power distribution method can effectively improve the functioning of an electric bus at different temperatures.