Integrated design is the main development trend of the spacecraft electrical system. The development status of electrical system in the new generation launch vehicle at home and abroad is reviewed, and the integrated architecture of electrical system based on the redundant system bus and integrated electronic architecture is put forward for the new generation medium Long March 8 (CZ-8) launch vehicle. The integrated design technology of electrical system is introduced from the aspects of system integration, power supply integration, software integration, test integration and telemetry integration. The integrated design technology will be used for the integration of system functions, and also for the breakthrough of the electrical system from traditional sub-system development to cross-system integration. Therefore, the integrated design technology of the electrical system can be used to simplify the test launch process and improve the launch capability, meeting the needs of a new generation of medium launch vehicles with low cost, high reliability, and fast launch.