Blended wing body （BWB） aircraft is one of the important development directions for future civil “green aviation” goal. In this paper, the open-loop flight characteristics of BWB aircraft are analyzed, and the requirements for airworthiness stability characteristics are proposed according to relevant regulations. A six-degree-of-freedom flight model for a typical BWB aircraft with back-supported engines was established. Feedback stabilization control laws were designed to meet the flight quality requirements, and control allocation was designed using the pseudo-inverse method to achieve commands of multiple control surfaces. Based on system simulation, an airworthiness evaluation was conducted for lateral-directional controllability and maneuverability under critical engine inoperative conditions. The simulation results demonstrate that the BWB aircraft still maintains sufficient residual controllability and maneuverability in the event of critical engine inoperative.