With the rapid advancement of the aviation and defense industries, improving gas turbine engine efficiency and reducing fuel consumption have become critical objectives. Accurate performance assessment is therefore essential, and thermodynamic behavior is commonly analyzed through cycle analysis. This chapter presents a parametric cycle analysis of a gas turbine aircraft engine, examining the effects of key design parameters—such as compressor pressure ratio, bypass ratio, Mach number, and fan pressure ratio—on thrust, specific fuel consumption, and overall efficiency. The objective is to determine optimal parameter ranges that enhance thrust and thermal efficiency while maintaining low fuel consumption, providing a systematic framework for preliminary engine design and optimization.