To guarantee safe and rapid flight of UAV in complex environments, in this paper, a hierarchical trajectory sequential convex programming method is proposed by dividing trajectory planning progress into three parts: Flight Path Planning, Safe Flight Corridors (SFC) Generation and Trajectory Sequential Convex Programming (SCP). Firstly, the Sparse A-star algorithm (SAS) is used to generate the initial flight path. The discrete path points provide the initial iteration value for SCP, which can improve the efficiency of trajectory solution. Subsequently, a SFC construction method which uses path segments as seeds is developed to ensure that SFC is continuous, and thus generating the convex feasible regions. Then, the sequential convex programming method is used to solve the trajectory rapidly. Consequently, the fixed-wing UAV can reach the terminal point in the shortest time within the constraints. The simulation results show that this method can ensure the safety of flight trajectory and satisfy timeliness requirements.