objective: To observe the variations of stress magnitude in the cervical vertebra exerted by vertical traction force from various angles and different points. Methods: The cervical vertebra model was produced by using elastic material of light (polycarbonate) and silica rubber(1:1). By calculating the arithmetical progression of interference fringe. The author judged the stress magnitude in the posterior edge of the C4-7 vertebral bodies when different kinds of pulling force acted on. Result: The interference pattern was seen clearly on the screen while the force acted on the model. When the pulling force acted on C1 or C2, the force was acting at an angle of 150the maximum of the stress presented in C4-5 and when the force acted at an angle of 25° the maximum stress presented in C5-6 and C6-7. Conclusion: The stress distributed upon the posterior edge of the vertebral joints is closely related to the points that the force aced on and the direction of the force． Appropriate points and direction of the pull should be selected according to the change of the lesion joints when manual manipulation is used for the treatment of cervical vertebral disease.