Aiming at the water landing of amphibious aircrafts，this paper presents a fluid-structure interaction (FSI) model of a certain amphibious aircraft head and analyzes the transient structural dynamic response of the head ditching by using the coupled Eulerian-Lagrange (CEL) method． Moreover，the stress，impact force and mass center velocity of the head at different ditching angles and vertical speeds are discussed． The results show that (1) the bottom pressure peak appears in the initial ditching stage and appears again with the heading up of the air-craft head; (2) during the ditching，the pressure of the head skeleton changes significantly; (3) with the de-crease of the hitting angle，the stress of the head reduces; and (4) both the head stress and the bottom impact force reduce with the decrease of ditching speed．