This paper introduces the requirements of design assurance system and supplier airworthiness management from airworthiness regulations. The paper analyses civil aircraft development process from the viewpoint of design assurance system, and interactive relationship between airframer and suppliers during the process of design requirements capture and validation, design result confirmation and verification, product integration and verification. Then supplier airworthiness management requirements based on nature of supplier’s work are presented, and supplier airworthiness management mode based on product category of working package is proposed. The mode solves supplier airworthiness management difficulties in type development process of domestic civil airframers and constructs effective design assurance system, which contributes to smooth type development.