Wire harness is ubiquitous in our life, ranging from alarm clock and radio to automobiles and airplanes. As long as there is an electrical system, there will be wire harness. The wiring harness of new energy vehicles is different from our general wire and cable structures because of its characteristics of high voltage, high current, heat resistance, sealing and anti-interference, so its design is different. The sealing requirements for the harness itself are also very high, which requires strict air tightness test for the harness. If the air tightness of the harness is not good, it may lead to signal transmission failure and functional equipment failure; Or short circuit or fire in case of water, or insulation failure and electric leakage.