In this paper, a novel guidance law is proposed which can achieve the desired impact speed and angle simultaneously for unpowered gliding vehicles. A guidance law with only impact angle constraint is used to produce the guidance profile, and its convergence in the varying speed scenario is proved. A relationship between flight states, guidance input and impact speed is established. By applying the fixed-time convergence control theory of error dynamics, an impact speed corrector is built with the above guidance profile, which can implement impact speed correction without affecting the impact angle constraint. Numerical simulations with various impact speed and angle constraints are conducted to demonstrate the performance of the proposed guidance law, and the robustness is also verified by Monte Carlo tests.