Objective:To evaluate the biomechanical stability of a cervical spine butterfly plate(CSBP)for unstable cervical spine.Method:Fourteen cervical spine specimens(C3～T1)were divided into two group:A and B.All intact,specimens were subjected to nondestructive testing in6loading modalities on a universal testing machine.A cadaveric model of complete C5～C6instability was produced in both groups.Specimens in group A were stabi -lized with CSBPs,and group B with Orion plates.The nondestructive testing was repeated to determine structural stability.Results:The injured spines stabilized with implants in both groups were significantly more stable than the intact specimens in all modes of testing(P<0.05).Stability of injured spines was increased most in flexion-extension,66%in flexion and60%in extension by CSBP while72%in flexion and71%in extension by Orion plate.The two constructs provided similar stability in6loading modalities(P>0.05).Conclusion:This study shows that CSBP provides biomechanical stability for unstable cervical spine.