A spinal rod , comprising: a rod assembly comprising a movable rod , a stationary rod and a cap , wherein the movable rod is on an upper side of the spinal rod and further comprises a second connecting portion and a second rod portion on the upper side of the second connecting portion , a diameter of the second connecting portion is larger than a diameter of the second rod portion , the stationary rod is on a lower side of the spinal rod and further comprises a first connecting portion and a first rod portion on the lower side of the first connecting portion , a diameter of the first connecting portion is larger than a diameter of the first rod portion , and the cap is between the stationary rod and the movable rod for fixing the movable rod and the stationary rod ; and an elastic assembly comprising a first elastic element and a second elastic element , wherein the elastic assembly is accommodated by the rod assembly, the first elastic element is between the cap and the stationary rod , a compression of the first elastic element by the movable rod shortens an overall length of the rod assembly, and the second elastic element provides a flexibility for movements of the movable rod and the stationary rod in a frontal plane and a sagittal plane, the spinal rod being characterized in that : the second elastic element is a rod structure partially accommodated by the movable rod and the stationary rod and passes through a center of the first elastic element , an end of the second elastic element is fixed inside the first rod portion , another end of the second elastic element is fixed inside the second rod portion , and the first rod portion , first connecting portion , the second rod portion , and the second connecting portion are of hollow structures. a rod assembly comprising a movable rod , a stationary rod and a cap , wherein the movable rod is on an upper side of the spinal rod and further comprises a second connecting portion and a second rod portion on the upper side of the second connecting portion , a diameter of the second connecting portion is larger than a diameter of the second rod portion , the stationary rod is on a lower side of the spinal rod and further comprises a first connecting portion and a first rod portion on the lower side of the first connecting portion , a diameter of the first connecting portion is larger than a diameter of the first rod portion , and the cap is between the stationary rod and the movable rod for fixing the movable rod and the stationary rod ; and an elastic assembly comprising a first elastic element and a second elastic element , wherein the elastic assembly is accommodated by the rod assembly, the first elastic element is between the cap and the stationary rod , a compression of the first elastic element by the movable rod shortens an overall length of the rod assembly, and the second elastic element provides a flexibility for movements of the movable rod and the stationary rod in a frontal plane and a sagittal plane, the spinal rod being characterized in that : the second elastic element is a rod structure partially accommodated by the movable rod and the stationary rod and passes through a center of the first elastic element , an end of the second elastic element is fixed inside the first rod portion , another end of the second elastic element is fixed inside the second rod portion , and the first rod portion , first connecting portion , the second rod portion , and the second connecting portion are of hollow structures. <EOS>