The present invention discloses an internal water cooling generator insulation tester. The insulation tester comprises a housing, two ends of the housing are respectively provided with electric cylinders, a pull rod is inlaid into a bottom end, close to a handle, of the front surface of the housing, two sides of the bottom end of the housing are respectively provided with grooves, the inner wallsof the grooves are rotationally connected with universal wheels, the bottom ends of the grooves are slidingly connected with sliding plates, the bottom ends of the sliding plates are fixedly connectedwith bulge structures, one end of a connection plate is fixedly connected with a spring, the bottom end of a top cover is provided with a storage box, and one side, close to the storage box, of the bottom end of the top cover is provided with a winding drum. The internal water cooling generator insulation tester is scientific and reasonable in structure and safe and reliable in usage, is providedwith sliding plates, can put the universal wheels into the housing, is provided with the pulling rod which is used to pull the tester for traveling, is provided with the electric cylinders to automatically operate the top cover, and is provided with the storage box and the winding drum to put auxiliaries required by measurement such as cables.