The developments and current status of ultra high voltage (UHV) alternating current (AC) and direct current (DC) transmission in China were reviewed in this paper. The UHV transmission historical developments in the past twenty years; the demand of development UHV transmission; the research results of the UHV key technologies including electromagnetic environment, over-voltage and insulation coordination, lightning performance, live-line working and equipment manufacture recent years in China; the design parameters and construction of UHV AC, UHV DC test and demonstration transmission lines, UHV AC, DC test bases and state grid simulation center were introduced. The suggestions at the aspects of UHV transmission future design, construction, commercial operation and maintenance were simply presented and discussed. The review and discussion are important for the safe and reliable operation of UHV grid in China and can be a reference for other countries that want to develop UHV AC and DC transmission.