An external lens connection structure for handset, comprising: a front add-on lens and/or a back add-on lens; a housing body, the housing body has a front side wall and a back side wall that are oppositely disposed, a space between the front side wall and the back side wall is adapted for fitting one end of a handset provided with a front camera and a back camera, a front add-on lens snapping opening is provided in the front side wall and corresponds to the front camera of the handset, and a back add-on lens snapping opening is provided in the back side wall and corresponds to the back camera of the handset, characterized in that, the front add-on lens snapping opening and the back add-on lens snapping opening both have two sections of protruding first ribs formed on the inner wall of the snapping opening and spaced apart in the circumferential direction; the front add-on lens and/or back add-on lens has a fitting head, the outer wall of the fitting head is formed with two protruding second ribs spaced apart in the circumferential direction and a protruding shoulder disposed opposite the second ribs, so as to form a snapping slot between the second rib and the protruding shoulder, the first rib is adapted for entering the snapping slot with the rotation of the snapping opening after the fitting head is inserted into the snapping opening, and the first rib, the second rib and the protruding shoulder are constructed in such a way that the fitting between the first rib and the snapping slot is changed from a clearance fitting to an interference fitting in the process of the first rib entering the snapping slot; wherein a surface of the first rib facing the second rib or facing the protruding shoulder is formed as a helical surface; or wherein a surface of the second rib facing the protruding shoulder or a surface of the protruding shoulder facing the second rib is formed as a helical surface. a front add-on lens and/or a back add-on lens; a housing body, the housing body has a front side wall and a back side wall that are oppositely disposed, a space between the front side wall and the back side wall is adapted for fitting one end of a handset provided with a front camera and a back camera, a front add-on lens snapping opening is provided in the front side wall and corresponds to the front camera of the handset, and a back add-on lens snapping opening is provided in the back side wall and corresponds to the back camera of the handset, characterized in that, the front add-on lens snapping opening and the back add-on lens snapping opening both have two sections of protruding first ribs formed on the inner wall of the snapping opening and spaced apart in the circumferential direction; the front add-on lens and/or back add-on lens has a fitting head, the outer wall of the fitting head is formed with two protruding second ribs spaced apart in the circumferential direction and a protruding shoulder disposed opposite the second ribs, so as to form a snapping slot between the second rib and the protruding shoulder, the first rib is adapted for entering the snapping slot with the rotation of the snapping opening after the fitting head is inserted into the snapping opening, and the first rib, the second rib and the protruding shoulder are constructed in such a way that the fitting between the first rib and the snapping slot is changed from a clearance fitting to an interference fitting in the process of the first rib entering the snapping slot; wherein a surface of the first rib facing the second rib or facing the protruding shoulder is formed as a helical surface; or wherein a surface of the second rib facing the protruding shoulder or a surface of the protruding shoulder facing the second rib is formed as a helical surface.