This paper investigates temperature control of an aircraft engine bleed air system, aiming at reducing ram air usage to reduce fuel consumption while maintaining fast temperature control response. To achieve both of the objectives, a system configuration is designed to control both ram-air and bypass flows. The analytical equations describing the system dynamics are derived and utilized in developing the overall bleed air system model. Optimal state feedback control and output feedback control are investigated for the temperature control system. The proposed configuration and control strategy are shown to be effective in minimizing ram air usage and maintaining fast temperature control in the meantime.