The use of XLPE insulation for high voltage and extra high voltage power cables is increasing. The new cable systems are installed in the field and inaccurate assembling of cable accessories could result in the precence of deffects.The after laying test is performed in the new cable system to check the quality of cable system installation.Also partial discharge test is usually carried out after cable system maintenance. In this book the author used a new technology for on-site withstand tests and partial discharge measurement of XLPE underground power cable system.In this book two methods of testing are presented, power frequency test and variable frequency (20-300 Hz)test.