The invention discloses a medical catheter leakage detector, wherein a water storage tank is disposed beside a sealing air cylinder; a push air cylinder is installed on the top part of the sealing air cylinder; a piston rod of the push air cylinder is fixed with a push plate; a sealing pressing rod is installed on a plate face of the push plate towards the sealing air cylinder; the sealing pressing rod has a hollow tubular structure; the sealing pressing rod is perpendicular to the push plate; a through hole is formed in the position on the push plate right facing the sealing pressing rod; a positioning hole is formed in the position on the cylinder wall of the sealing air cylinder right facing the sealing pressing rod; a sealing sleeve is embedded in the positioning hole; and the sealing sleeve is inwards limited by a step face of the inner wall of the positioning hole. The medical catheter leakage detector disclosed by the invention has the advantages of a simple structure, easy assembly, small occupied space and low cost; sealing effects are good during detection; the sealing effects can be adjusted through adjustment of a stroke of the push air cylinder; different detection demands can be satisfied; operations are simple, convenient and rapid on the premise of ensuring accurate and reliable detection results; eight or even more medical catheters can be detected at a time; detection time is short; and detection efficiency is high.