Aircraft and precooled engine efficient matching work is a key issue in the thermal cycle design of precooled engines, to solve this problem, an aircraft/precooled turbine engine integrated design method considering the fuel precooling impact mechanism is newly proposed. The impact of n-decane, ammonia, and hydrogen fuel precooling on aircraft design parameters and engine thrust requirements is revealed. Furthermore, a parameter optimal design method for fuel precooled engine is carried out to satisfy the multi-objective performance requirements of high specific thrust, low fuel consumption, high exergy efficiency, and low weight. The simulation results show that the n-decane fuel precooled engine reduces the takeoff weight of the aircraft by 4.23% and the fuel load by 11.6%, which has a better comprehensive performance than that of ammonia and hydrogen. Ammonia fuel has the maximum precooling heat sink and performance improvement space. After multi-objective optimization, it increases the maximum specific thrust by 7.3%, reduces fuel consumption by 2.2%, and improves the engine exergy efficiency by 2.7%, with only a 1.3% increase in rotating component weight. Ammonia and n-decane dual fuel precooling can achieve complementary advantages of high combustion heat value and high precooling heat sink, making it an ideal precooled engine scheme.