China Fusion Engineering Test Reactor (CFETR) is now in the conceptual design phase. The main objective of CFETR is demonstration of fusion energy with 50 ∼ 200 MW fusion power, fuel cycle of T self-sustained and steady-state operation with duty cycle of 0.3 ∼ 0.5. The design of CFETR involves complex system structure, and there are complex constrains between physics and engineering. Between optimization of performance parameters and design of main structure and key components, numerous data exchange and iterative optimization are necessary for optimal design of sub-systems. To do the optimization design, a CFETR system code is under development. The main technical schemes for system code include: a physical design platform and various engineering design modules are developed, then a global framework integrates them by standard interfaces and communication technologies; and a standard material and design criterion database unifies the reference data for the system code. The detailed study will be presented in this conference.