A connector structure of an ink pouch, comprising: a connector body, which comprises a joining section, a sealing section joined to the joining section, and an ink passage extending in a longitudinal direction through the joining section and the sealing section, the sealing section having a top surface on which a fitting peg, which is hollow, is formed to extend upward from a circumference of the ink passage, the top surface of the sealing section being formed with a plurality of insertion slots that are extended downward and spaced from each other along a circumference of the fitting peg by a predetermined interval, the sealing section having an external circumferential surface that is partly and inwardly recessed to form an annular retaining groove, the annular retaining groove being in communication with ends of the plurality of the insertion slots; a sealing cap having a top surface that is partly recessed downward in a central portion thereof to form a pressing section, the sealing cap having a bottom surface that is partly recessed upward to form a fitting trough corresponding in position to the pressing section, the bottom surface of the sealing cap being provided with a plurality of engaging and retaining sections projecting therefrom and along a circumference of the fitting trough and spaced from each other by a predetermined interval, the engaging and retaining sections each comprising an insertion arm extending downward from the bottom surface of the sealing cap and an engaging block protruding outward from an end of the insertion arm; and a flexible plug having an outside diameter that is greater than an inside diameter of the ink passage of the connector body; wherein to combine, the flexible plug is positioned in the fitting trough of the sealing cap, and the insertion arms of the engaging and retaining sections of the sealing cap are respectively inserted into the insertion slots of the connector body, such that the engaging blocks protrude into the annular retaining groove of the connector body to securely combine the sealing cap and the connector body together, and wherein the fitting peg is located in the fitting trough and the flexible plug closes the ink passage. a connector body, which comprises a joining section, a sealing section joined to the joining section, and an ink passage extending in a longitudinal direction through the joining section and the sealing section, the sealing section having a top surface on which a fitting peg, which is hollow, is formed to extend upward from a circumference of the ink passage, the top surface of the sealing section being formed with a plurality of insertion slots that are extended downward and spaced from each other along a circumference of the fitting peg by a predetermined interval, the sealing section having an external circumferential surface that is partly and inwardly recessed to form an annular retaining groove, the annular retaining groove being in communication with ends of the plurality of the insertion slots; a sealing cap having a top surface that is partly recessed downward in a central portion thereof to form a pressing section, the sealing cap having a bottom surface that is partly recessed upward to form a fitting trough corresponding in position to the pressing section, the bottom surface of the sealing cap being provided with a plurality of engaging and retaining sections projecting therefrom and along a circumference of the fitting trough and spaced from each other by a predetermined interval, the engaging and retaining sections each comprising an insertion arm extending downward from the bottom surface of the sealing cap and an engaging block protruding outward from an end of the insertion arm; and a flexible plug having an outside diameter that is greater than an inside diameter of the ink passage of the connector body; wherein to combine, the flexible plug is positioned in the fitting trough of the sealing cap, and the insertion arms of the engaging and retaining sections of the sealing cap are respectively inserted into the insertion slots of the connector body, such that the engaging blocks protrude into the annular retaining groove of the connector body to securely combine the sealing cap and the connector body together, and wherein the fitting peg is located in the fitting trough and the flexible plug closes the ink passage.