The invention discloses a mechanism for manufacturing a leakage-proof valve port. The mechanism comprises elements such as a paper frame and the like, wherein the paper frame is mounted between a base and a top base; a PE (polyethylene) membrane frame is mounted on the lateral side of the paper frame; a tension swing roller is mounted on the lateral side of the PE membrane frame; a cutter groove roller and a cutter roller are mounted on the lateral side of the tension swing roller; a layering roller is mounted on the lateral side of the cutter roller; a first PE membrane traction roller and a second PE membrane traction roller are mounted behind the layering roller; a travel adjusting roller is arranged between the first PE membrane traction roller and the second PE membrane traction roller; a first compression roller and a second compression roller are mounted on the lateral side of the second PE membrane traction roller; a pull-apart roller is arranged on the lateral side of the second compression roller; a clamp roller is mounted on the lateral side of the pull-apart roller; a paper sticking roller is mounted on the lateral side of the clamp roller and is matched with the clamp roller; and a paper ejecting cutter is mounted on the clamp roller. According to the invention, the mechanism can directly manufacture the leakage-proof valve port with interior closing performance in an online manner; and therefore, a valve port paper bag with a leakage-proof valve port is produced automatically.