Addressing the demand for small turbofan engines in the 600–800 kg thrust range for light business jets, this paper proposes three overall performance schemes with varying levels of technological maturity through comparative analysis of existing turbofan engine design parameters, combined with cycle parameter optimization and future technological trends. By constructing an overall performance model for a small separate-flow turbofan engine, three engine schemes with thrust levels of 600 kg, 700 kg, and 800 kg were designed, and control laws and off-design point characteristics were analyzed. The results indicate that increasing the turbine inlet temperature, compressor pressure ratio, and bypass ratio significantly enhances engine performance. Among the schemes, an improved configuration with a booster stage achieved a 19% thrust increase at a lower turbine inlet temperature, demonstrating the effectiveness of configuration innovation. This study provides theoretical and technical references for the design and optimization of small turbofan engines.