Abstract: For the hydropower station installed with 1000 MW hydro-generator unit, the rated voltage of the generator will reach 24 kV or 26 kV because of the rated current limit (28 kA) of the main circuit device. It is the first time for a hydropower station in the world to adopt a generator-unit with such a high-level voltage. As the insulation material, structure and technique used in stator winding, to a large extent, reflect the design and manufacturing quality of the generator, stator winding insulation for 1000 MW hydro-generator unit with 24 kV and 26 kV rated voltage becomes a crucial technology. Based on the simulation results of the winding insulation for 1000 MW hydro-generator unit with 24 kV and 26 kV rated voltage of Wudongde Hydropower Station and Baihetan Hydropower Station by Harbin Electric Corporation and Dongfang Electric Machinery Co., Ltd., the winding insulation for generators with high voltage and its experimental research are analyzed and summarized. Suggestions for the application of the insulation technology in specific projects are also proposed.