An integral sliding mode guidance law (ISMGL) com-bined with the advantages of the integral sliding mode control (SMC) method is designed to address maneuvering target inter-ception problems with impact angle constraints. The relative mo-tion equation of the missile and the target considering the impact angle constraint is established in the longitudinal plane, and an in-tegral sliding mode surface is constructed. The proposed guidance law resolves the existence of a steady-state error problem in the traditional SMC. Such a guidance law ensures that the missile hits the target with an ideal impact angle in finite time and the missile is kept highly robust throughout the interception process. By adopting the dynamic surface control method, the ISMGL is designed con-sidering the impact angle constraints and the autopilot dynamic characteristics. According to the Lyapunov stability theorem, all states of the closed-loop system are finally proven to be uniformly bounded. Simulation results are compared with the general sliding mode guidance law and the trajectory shaping guidance law, and the findings verify the effectiveness and superiority of the ISMGL.