Purpose <p>Cervical spondylosis is a common disease. The effect of sagittal cervical alignment on three-dimensional (3D) movement of the cervical spine is not clear. This study aimed to assess the effect, to provide a method for evaluating therapeutic efficacy in the future.</p> Methods <p>Eighty four patients with cervical spondylosis were sequentially investigated. Patients were divided into three groups equally according to the curve of neck, lordosis, straight and kyphosis. 3D kinematic movements of the cervical spine were registered by 3D motion acquisition system. The range of the primary motion and coupled motions were analyzed.&#xa0;</p> Results <p>During left bending, the range of coupled ipsilateral rotation in the kyphosis group(14.34°±7.00°) is smaller than that in the straight group(20.02°±8.18°) (<i>P</i> &lt; 0.05). During right bending, range of coupled ipsilateral rotation in the kyphosis group(-15.64°±10.60°) is smaller than that in the lordosis group(-22.45°±9.25°)(<i>P</i> &lt; 0.05).&#xa0;During left and right rotation, range of coupled extension in the kyphosis group(−10.42°±12.44°, −12.63°±13.32°) is smaller than that in the lordosis group(−18.10°±13.17°, −21.54°±16.24°)(<i>P</i> &lt; 0.05).</p> Conclusions <p>The patients with cervical kyphosis showed a decreased range of coupled ipsilateral rotation during lateral bending and a decreased range of coupled extension during rotation. Progressive deterioration of cervical curvature was associated with a corresponding reduction in the ratio of coupled rotation to main right bending, as well as the ratios of coupled extension to main rotation. However, there was no difference in the range of main motion and the patterns of coupled motion in patients with cervical spondylosis among lordosis, straight and mild kyphosis.</p>