For multiple hypersonic vehicles cooperative to attack a stationary target with time-varying velocities in dive phase, a finite-time cooperative guidance law is proposed. Firstly, this paper analyzes the characteristics of hypersonic vehicles in dive phase, and divides the terminal guidance process into two parts; that is, two relative motion equations are established to describe longitudinal and lateral directions. Secondly, in the longitudinal line of sight direction, the relative position difference and line-of-sight velocity difference between each vehicle participating in the attack missions and its neighbors are introduced as error terms into the guidance law. Finally, in order to achieve the convergence of the horizontal and vertical line-of-sight angles, a finite-time sliding mode guidance law is designed, and an adaptive disturbance observer to estimate the upper bound of time-varying disturbance is propose. The Lyapunov function is used to prove the finite time convergence of the proposed cooperative guidance law, and the simulation results verify the correctness and effectiveness of the designed cooperative guidance law.