A leakproof structure of the lamp holder of an infrared lamp tube, including: an elongated housing, whose section is concave to form an accommodating space, the bottom of the elongated housing is provided with at least one installation hole; at least one lamp holder corresponding to the installation hole arranged at the bottom of the elongated housing; at least one halogen bulb arranged on the lamp holder, and the upper section of the halogen bulb protrudes into the accommodating space; a light-transmitting board arranged on the top of the elongated housing; two left and right covers arranged on the left and right sides of the elongated housing respectively, and a flow hole is provided on the two left and right covers relative to the accommodating space; wherein the installation hole of the elongated housing is a screw hole, and the lamp holder includes: a hollow seat, having a ring shaped body formed on the top thereof, a protruding thread body that can be locked in the installation hole is formed on the ring shaped body, a first through hole is formed in the protruding thread body, below the first through hole is connected with a second through hole with a larger diameter, and an internal screw thread is formed at the bottom of the second through hole; an O-ring washer, which is sleeved on the bottom of the outer peripheral edge of the protruding thread body, and is pressed against the bottom edge of the elongated housing by the ring shaped body; a waterproof plug, which is tightly placed in the second through hole, the upper part of the waterproof plug is provided with a receiving hole for the lower part of the halogen bulb to be embedded, and an electrical pin of the halogen bulb protrude out the bottom of the waterproof plug; and an internal nut, which is locked in an internal screw thread at the bottom of the second through hole, for pressing the upper part of the waterproof plug against the bottom edge surface of the first through hole, so that the first through hole forms a waterproof closed state, and the internal nut has a third through hole. at least one lamp holder corresponding to the installation hole arranged at the bottom of the elongated housing; at least one halogen bulb arranged on the lamp holder, and the upper section of the halogen bulb protrudes into the accommodating space; a light-transmitting board arranged on the top of the elongated housing; two left and right covers arranged on the left and right sides of the elongated housing respectively, and a flow hole is provided on the two left and right covers relative to the accommodating space; wherein the installation hole of the elongated housing is a screw hole, and the lamp holder includes: a hollow seat, having a ring shaped body formed on the top thereof, a protruding thread body that can be locked in the installation hole is formed on the ring shaped body, a first through hole is formed in the protruding thread body, below the first through hole is connected with a second through hole with a larger diameter, and an internal screw thread is formed at the bottom of the second through hole; an O-ring washer, which is sleeved on the bottom of the outer peripheral edge of the protruding thread body, and is pressed against the bottom edge of the elongated housing by the ring shaped body; a waterproof plug, which is tightly placed in the second through hole, the upper part of the waterproof plug is provided with a receiving hole for the lower part of the halogen bulb to be embedded, and an electrical pin of the halogen bulb protrude out the bottom of the waterproof plug; and an internal nut, which is locked in an internal screw thread at the bottom of the second through hole, for pressing the upper part of the waterproof plug against the bottom edge surface of the first through hole, so that the first through hole forms a waterproof closed state, and the internal nut has a third through hole. a hollow seat, having a ring shaped body formed on the top thereof, a protruding thread body that can be locked in the installation hole is formed on the ring shaped body, a first through hole is formed in the protruding thread body, below the first through hole is connected with a second through hole with a larger diameter, and an internal screw thread is formed at the bottom of the second through hole; an O-ring washer, which is sleeved on the bottom of the outer peripheral edge of the protruding thread body, and is pressed against the bottom edge of the elongated housing by the ring shaped body; a waterproof plug, which is tightly placed in the second through hole, the upper part of the waterproof plug is provided with a receiving hole for the lower part of the halogen bulb to be embedded, and an electrical pin of the halogen bulb protrude out the bottom of the waterproof plug; and an internal nut, which is locked in an internal screw thread at the bottom of the second through hole, for pressing the upper part of the waterproof plug against the bottom edge surface of the first through hole, so that the first through hole forms a waterproof closed state, and the internal nut has a third through hole.