Occupant posture change during autonomous emergency braking (AEB) and occupant kinematics in frontal collision were simulated using finite element (FE) models. The human body FE model, THUMS, was used to represent the occupant. Muscle elements were activated for simulating reactions of the occupant retaining the initial posture. Small female, mid‐size male and large male occupants were assumed. A forward deceleration of 9.8 m/s² was applied to simulate braking by AEB. The emergency locking retractor (ELR) was activated before the time of collision with AEB while in collision without AEB. Frontal collision was simulated by applying a collision pulse to the model. The pre‐tensioner and the airbag were activated. For each occupant, injury values were compared between cases with and without AEB. It was assumed that the collision speed was reduced by 20 km/h with AEB. The occupant moved forward during braking. Tensile force was generated in the seatbelt prior to the collision. The distance between the occupant and the steering wheel (airbag) at the time of collision was shorter than that without AEB. However, the maximum forward displacement was smaller and the injury values were lower with AEB. Similar trends were commonly observed in the different body size models.