Reentry trajectory design for hypersonic glide vehicle with multiple constrains is a critical issue in the field of aircraft guidance and control. In this paper, we attempt to handle the constrained reentry trajectory design problem using the whale optimization algorithm. First, the constrained trajectory design problem is converted to unconstrained using the penalty function method. Then, the penalty factor coefficients of the resulting synthesized fitness function are calculated from pairwise comparison judgments of the analytic hierarchy process. Finally, combined with the suggested constraint handling method, the improved WOA is applied to the reentry trajectory design problem of HGV successfully. Numerical simulations show that the proposed optimization strategy is competitive in searching accuracy and convergence speed.