The invention discloses a coil heat exchanger with the automatic defrosting function. The coil heat exchanger with the automatic defrosting function comprises a plurality of heat exchange tubes, wherein a heat exchange unit is formed by the heat exchange tubes. The multiple heat exchange tubes are installed on an outer frame with both the front side and the rear side open. The outer wall of each heat exchange tube is winded by a coil piece in a spiral manner. One end of each coil piece is fixed to one end of the heat exchange tube winded by the coil piece, and the other end of the coil piece is connected with a pull rod. Each pull rod stretches out of the outer frame and is connected with a pull plate arranged on the outer side of the outer frame. The pull plate is connected with a crank through a connecting rod. The crank is connected with a motor. According to the coil heat exchanger with the automatic defrosting function, an automatic movement mechanism is used for driving the coilpieces to move on the surfaces of the heat exchange tubes so as to prevent frost layers outside the heat exchange tubes from gathering or solidifying, the thermal resistance of an evaporator is reduced, the heat transfer temperature difference is reduced, and the pressure ratio of a refrigeration compressor is lowered.