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Background: Advanced Driver Assistance Systems (ADAS) in combination with the updated passive safety systems is the key to reduce future crash severity and improve the occupant protection performance.The autonomous braking system is able to reduce crash speeds and the crash severity levels significantly.Occupant kinematics would be changed due to certain pre-impact braking, which has not been considered in most in-lab crash tests.Objective: This study aims to assess the effects of different pre-impact braking events on the occupant kinematics,as well as the injury possibility, by using full frontal impact simulation.Method: MADYMO simulation and validation of a 50km/h frontal crash test were carried out for the following detailed investigation of dummy forward displacements due to pre-impact braking.The influences of different pre-impact scenarios (with the initial velocity of 80km/h, all leading to equal 50km/h before the crash phase), are considered in terms of vehicle accelerations.Occupant kinematics and potential injury possibility under different braking load cases were analyzed in the study by introducing the human body model.The evaluation is mainly concerning about dummy kinematics as well as contact risk between the dummy and vehicle interior.Besides, the study reviews the contribution of the human model in comparison with the dummy model and discusses the potential of using the human model for detailed simulation.Results: The result shows that the occupant kinematics of the impact with pre-impact braking is different with that of the C-NCAP 50km/h frontal impact.This difference makes the dummy have high risk of airbag flapping, and the belt retractor has less efficiency in pretensioning (the maximum pull-in amount was reduced about 13mm).Conclusions: This study recommends changes to occupant restraint systems to fit requirements of occupant forward displacement caused by pre-impact braking.The in-lab crash test considering emergency braking prior to the impact is highly recommended as well for detailed study, for further improvement of the occupant protection performance.