Railway vehicle and side wall structure thereof

The side wall structure comprises a side door wall plate part, a first side wall part and a second side wall part which are connected in sequence, the first side wall part comprises an upper side wallplate part, a lower side wall plate part and a middle side wall plate part located between the upper side wall plate part and the lower side wall plate part, and the height of the middle side wall plate part is matched with that of a side door; the upper side wall plate part, the lower side wall plate part and the second side wall part are equal in thickness and are all greater than the middle side wall plate part in thickness; the length of the first side wall part is equal to that of the side door wallboard part; the middle side wall plate part and the second side wall part are connected through a transition beam; the transition beam comprises an outer beam wall, and a first side beam wall and a second side beam wall which are fixedly arranged at two ends of the outer beam wall; the first side beam wall is fixe