To meet the varying load demands and improve the efficiency of the power system during aircraft flights in the aviation field， a hybrid power system architecture combining direct ammonia solid oxide fuel cells （SOFCs） and lithium batteries is established. A rule-based energy distribution strategy is adopted for the comparative analysis of parameters such as efficiency and power-to-mass ratio of the hybrid system within the typical flight envelope. The aim is to find an optimal energy supply scheme for the entire flight process of the aircraft.In the case of the BAe.146， a four-engine turbofan short-range transport aircraft， a net power generation efficiency of 53.32% and a power-to-mass ratio of 0.491 3 kW/kg are achieved. Furthermore， it has been found that the output power and power generation efficiency of the SOFC system decrease with increasing altitude. These results indicate that the direct ammonia SOFC-lithium battery hybrid power system is capable of meeting the energy demands of different flight phases and holds promising application prospects in the aviation field.