Objective Based on the dummy model, to study the relationship between different backrest angles and neck injuries under the effect of horizontal negative acceleration (-Gx ). Methods The dummy model was fixed on the base of the acceleration platform facing the orbital direction, and the backrest angle was set at 17°, 22°, 30°, respectively. Each experimental group performed 10 repeated tests according to the same acceleration curve, differences between the upper and lower acceleration of the cervical spine under the same -Gx conditions were compared, and the neck injury criteria (NIC) was calculated and compared through curve fitting. Results The time-acceleration curves of the upper and lower cervical spine in the anteroposterior and vertical directions had the same shape with peak differences. In the anteroposterior direction (X-axis), the acceleration peak of the 22° backrest angle experimental group was slightly higher than that of 17° and 30° backrest angle experimental groups, but in the vertical direction (Z-axis), the acceleration peak of the 22° backrest experimental group was lower than that of 17° and 30° backrest angle experimental groups. In the anteroposterior and vertical directions, the NICmax measured by 22° backrest angle experimental group was relatively smaller, NICmax measured by 30°backrest angle experimental group was in the middle, and NICmax measured by 30° backrest angle experimental group was relatively larger. Conclusions There was a nonlinear relationship between the backrest angle and theneck injury. The neck injury of the dummy model with the backrest angle of 22° was smallest under the effect of -Gx in this experiment.