The invention provides a hidden type reinforcing node of a side span node of a wood structure traditional architecture and a preparation method of the hidden type reinforcing node, and belongs to the technical field of protection works for the wood structure traditional architecture. Beam column components are connected into a whole through connection long pull rods, reinforcing plates and fixing nuts which are installed inside a beam column node in a hidden mode, so that the pull-out resistance capacity and rigidity of the node are improved, and the appearances of the components are recovered by filling epoxy resin adhesives into notches. By means of the hidden type reinforcing node of the side span node of the wood structure traditional architecture and the preparation method of the hidden type reinforcing node, the bearing capacity of the node can be improved, the wood structure traditional architecture is protected, and the damage to the structural appearance caused by a former external reinforcing method is avoided.