The invention provides an interface conversion device for an alternating current charging pile. The device comprises a side socket of the charging pile, a side socket of a low-speed electric vehicle, an electric energy conversion circuit and a controller, wherein the electric energy conversion circuit is connected between a power contact of the side socket of the charging pile and the side socket of the low-speed electric vehicle, and is used for converting the alternating current into the direct current applicable for the low-speed electric vehicle; and the controller is connected with a communication contact of the side socket of the charging pile, the side socket of the low-speed electric vehicle and the electric energy conversion circuit, and is used for receiving the maximum power supply information provided by the charging pile and the charging relevant information provided by the low-speed electric vehicle and outputting a control signal to the electric energy conversion circuit according to the maximum power supply information and the charging relevant information. The device provided by the invention can solve the problems in the prior art that a charging interface for an electric vehicle charging pile is single, can not meet diversified charging requirements and is not applicable for charging low-speed electric vehicles.