A side sliding door of a railway vehicle comprises a door body (100), and a driving device for the opening and closing of a doorway. An outer surface of the door body (100) is flush with an outer surface of the vehicle body when the door body (100) is closed. A movement track of the door body is arranged as an arc-plus-linear reciprocating motion. The outer surface of the door body is flush with the outer surface of the vehicle body when the door body is closed, so that there exists no height difference between the vehicle body and a doorway of the side sliding door. Snow accumulation at doorway under an extreme cold working condition is avoided, and then the risk of a door body being frozen is reduced.