Aiming at the guidance problem under impact angle constraint for homing missile against ground targets, a new adaptive robust nonlinear terminal guidance law was proposed in this paper. According to nonlinear kinetic relationship between the missile and target in vertical plane, a mathematic model was formulated while the motion of target and the system structure perturbation were regarded as limited disturbances. Based on the ideas of zeroing the rate of line-of-sight (LOS)angle and the impact angular tracking error, a nonlinear control strategy was contrived to obtain adaptive robust guidance law by adopting Nussbaum-type gain technique under a desired impact angle. The stability of guidance system in finite time is strictly proven by using Lyapunov stability theory. Finally, the numerical simulation verifies the effectiveness of the proposed scheme.