A socket spanner for rails comprises a barrel body, a handle is arranged on the upper portion of the barrel body, a barrel-shaped spanner matched with a nut is connected to the lower end of the barrel body, and the upper end of the barrel body is connected with an end cover. The socket spanner for rails is characterized in that a clamping rod is arranged in the barrel body in a sleeved mode, the upper end of the clamping rod penetrates through a center hole of the end cover and then is connected with an auxiliary handle, the lower end of the clamping rod is connected with a nut clamping device, and a center hole which ensures that the nut clamping device can move up and down is formed in the upper end face of the barrel-shaped spanner. When the structure is adopted for mounting and dismounting nuts, a worker does not need to bend down to place the socket spanner to the nut of a bolt in a sleeving mode and can place the socket spanner for rails to the nut of the bolt in a sleeving mode with the body being upright, and the handle only needs to be rotated; in particular, when the nut is dismounted, the nut is clamped through the auxiliary handle, the nut is made not to fall at will, and the nut is made to fall when needing to be placed. Operation is easy, using is convenient, the labor intensity is greatly lowered, and therefore the working efficiency is improved.