A nonsingular variable structure guidance law for anti-ship missile against maneuvering warship was designed based on variable structure control theory. The guidance law based on the so-called relative heading error angle between the relative velocity vector and the line of sight that to be controlled to zero was suitable for random original line throwing and target heading angle, the so-called relative heading error angle between the relative velocity vector and the line of sight was chosen as the output to be controlled to zero. Meanwhile, the falling angle constraint was chosen to be terminal constraint condition in this article. Simulation results show that the miss distance and the falling angle constraint are well satisfied by using the designed guidance law in any original heading angle.