It is a cooler for internal hydrogen water cooling when the temperature rises due to the turbine generator’s heat generation in the rotation. Since the heat transfer of hydrogen is higher than that of air, the generator of larger power can be cooled. It adopts the cooling elements developed based on the hydrogen cooler design. The cooling tube may adopt stainless steel and copper alloy tube with excellent corrosion resistance. Fin may adopt copper and aluminum plate fin with concave-convex surfaces. The cooling tube and fin undergo the close combination of expanded tube by expanded joint, so as to improve the heat transfer efficiency. Aiming at the large capacity, small wind resistance, compact and lightweight design, based on the customer needs, the product adopts the stepless design and is an excellenthydrogen cooler.