This paper presents an event-triggered control method for the hybrid power supply (HPS) of fuel-cell heavy-duty truck. The HPS consists of a fuel cell, a lithium-ion battery and a supercapacitor, which can supply the power according to their characteristics and the load demand. The proposed event-triggered method is developed by integrating the event-triggered control strategy into the conventional proportional-integrational (PI) control strategy. Hence, if the triggering condition is satisfied, the PI control scheme is activated; otherwise, the PI control scheme is suspended and the control signal is kept still. Accordingly, the proposed event-triggered method inherits the advantages: i) the lower computational burden without sacrificing the regulation performance, ii) reduction of the switching actions for lower switching loss. A series of simulation studies have been conducted based on the digital model of the HPS of heavy-duty truck, under different load profiles including hydraulic system profile and speed mission profile. The simulation results demonstrate the effectiveness of the proposed event-triggered method for the HPS of fuel-cell heavy-duty truck.