In order to enhance the safety of FlexRay protocol applied in avionic network in aircraft complied with CCAR23,a heartbeat message structure is defined and a membership protocol algorithm is designed and implemented for FlexRay protocol based on its transmission characteristics.The algorithm consists three phases:status announcement in static segment, negotiation in dynamic segment and decision-making in network idle time.It uses processes hosted by the node as management target and enable the reintegration of a process.Within one cycle,it can identify n faults in a 2n+1 processes member group while at least n+1 process are without fault.Test result shows that the algorithm satisfies the validity,agreement and self-diagnosis requirements of membership protocol.