UHV AC transformer is one of the core equipment of UHV AC power transmission project, this paper analyzes the main characteristics of transformers used in 1000 kV UHV AC transmission project in terms of design, manufacturing, testing and transportation, etc. This paper introduces the engineering application of UHV transformer in China, the breakthrough in the key raw materials and components, and the achievements obtained in the standardization of UHV transformer. With the continuous development of China's UHV power grid, UHV transformer technology has made considerable progress. This paper analyzes the characteristics and applicability of a series of innovative products such as the UHV step-up transformer, 1000 kV step-down 220 kV transformer, UHV large capacity transformer, and the Advanced Site Assembly (ASA) UHV transformers. Engineering application indicates that UHV transformer in China has advanced technology and reliable operation. Finally, it makes a prospect of the development of UHV transformer in the aspects of performance improvement, domestic level and operation and maintenance. This work is supported by Science and Technology Project of State Grid Corporation of China (No. SGTYHT15-JS-191).