A refrigerant pipe connection structure for an air conditioner comprising: a connection member connected with a heat exchanger which includes a male screw part provided at an outer surface thereof and a slope provided at an end thereof; an external refrigerant pipe connected with the connection member which includes a flare provided at an end thereof, said flare of the external refrigerant pipe corresponds to the slope of the connection member to form close contact with each other, and a coupling member for mechanically coupling the connection member and the external refrigerant pipe with each other, which includes a female screw part corresponding to the male screw part of the connection member, said female screw part being provided at an inner surface of the coupling member and the coupling member further including an adhesion part provided in the other portion of the inner surface of the coupling member opposite to the female screw part, said adhesion part has a profile corresponding to the flare of the external refrigerant pipe, wherein the female screw part is screwed directly to the male screw part and the adhesion part presses an outer surface of the flare and is adhered directly to the flare; wherein a material of the connection member is different from a material of the external refrigerant pipe, and a material of the coupling member is substantially same as the material of the external refrigerant pipe in view of a galvanic potential, so that a contact area between the external refrigerant pipe and the coupling member is configured to prevent galvanic corrosion, wherein the connection member, the external refrigerant pipe and the coupling member are made of metal; characterized in that the material used to form the external refrigerant pipe is Al1060-O and the material used to form the coupling member is Al7075-O. a connection member connected with a heat exchanger which includes a male screw part provided at an outer surface thereof and a slope provided at an end thereof; an external refrigerant pipe connected with the connection member which includes a flare provided at an end thereof, said flare of the external refrigerant pipe corresponds to the slope of the connection member to form close contact with each other, and a coupling member for mechanically coupling the connection member and the external refrigerant pipe with each other, which includes a female screw part corresponding to the male screw part of the connection member, said female screw part being provided at an inner surface of the coupling member and the coupling member further including an adhesion part provided in the other portion of the inner surface of the coupling member opposite to the female screw part, said adhesion part has a profile corresponding to the flare of the external refrigerant pipe, wherein the female screw part is screwed directly to the male screw part and the adhesion part presses an outer surface of the flare and is adhered directly to the flare; wherein a material of the connection member is different from a material of the external refrigerant pipe, and a material of the coupling member is substantially same as the material of the external refrigerant pipe in view of a galvanic potential, so that a contact area between the external refrigerant pipe and the coupling member is configured to prevent galvanic corrosion, wherein the connection member, the external refrigerant pipe and the coupling member are made of metal; characterized in that the material used to form the external refrigerant pipe is Al1060-O and the material used to form the coupling member is Al7075-O.