Aircraft engines involve multiple closely coupled disciplines. Owing to difficulties in bridging disciplines and the large workload of model interface adaptation, recent research has focused mainly on single-discipline and professional simulations, which have difficulty effectively reflecting the coupling relationships between various components and subsystems of aircraft engines. Therefore, this paper proposes an enhanced model of a whole aircraft engine system and provides a standard for evaluating the completeness of the model. On the basis of the engine performance model, a multisystem co-simulation model is formed by introducing detailed mechanism models of each subsystem. The digitally co-simulation of multisystem and multidisciplinary models can reveal the compatibility between subsystems in the design process in advance, mutually verify the rationality and completeness of the design results, and improve the success rate and credibility of the scheme design.