The regulations and requirements of current CCAR 25 aim at the traditional aircrafts which use mechanical flight control system. With the widespread use of FlybyWire (FBW) flight control system, some new airworthiness requirements are generated about the integrity of digital signals, and AC 25.1309 provisions, in order to achieve the same or equivalent safety level of traditional design. This paper introduces the FBW safety assessment process of civil aircraft, and the applicable airworthiness requirements and verification methods were presented based on the features of FBW safety design.