Abstract: A sliding mode midcourse guidance law considering the missile’s dynamics of autopilot is proposed for the transition problem from midcourse guidance to terminal guidance with multiple constraints. Firstly, a motion model between missile and target is established on the basis of the first order missile dynamics. According to this model, a nonsingular terminal sliding mode surface is designed, and the adaptive sliding mode reaching law is used to design a finite time convergent midcourse guidance law. Secondly, the extended state observer is employed to estimate the maneuvering information of the target, and the estimated value is applied to the nonsingular sliding mode midcourse guidance law. Finally, based on the finite time theory, the finite time convergence characteristics of the midcourse guidance law are analyzed. Numerical simulation results show that the proposed midcourse guidance law has strong robustness and small handover error.