The invention discloses a buffer with a dismantling device for a railway vehicle. The buffer comprises a mounting base, two or more elastic bodies, a draw bar and a locking piece. The elastic bodies are mounted on the draw bar in a sleeved mode and are locked through the locking piece. The buffer further comprises a rotary shaft drum, a snap bolt and a guide block. The mounting base is provided with a first mounting hole. The rotary shaft drum is located in the first mounting hole. The inner wall of the first mounting hole of the mounting base is provided with a guide groove. The guide block is provided with a rotary shaft hole. The guide block is connected with the guide groove in a sliding mode and is fixedly connected with the end face of the mounting base through the snap bolt. A rotary shaft is arranged on the periphery of the rotary shaft drum. The rotary shaft extends into the rotary shaft hole of the guide block. The rotary shaft drum is provided with a second mounting hole. A partition board is arranged in the second mounting hole. The partition board is provided with a partition board hole. The draw bar penetrates through the partition board hole, and the two sides of the partition board are respectively provided with at least one elastic body. The buffer is provided with a guide structure, so that the buffer is prevented from skewing and getting stuck in the dismantling process.