Abstract: For gas over oil actuator, a key equipment of emergency shut down for natural gas pipeline protection commonly used in China, many design units, construction units and users have insufficient understanding to the functions of its electronic line break protection. Based on the development and application of this product, this paper introduces in detail the basic parts, operating principles and functional characteristics of the electronic line break protection unit of gas over oil actuator common in the natural gas pipelines. Furthermore, this paper expounds the standards and specifications compulsory both at home and abroad in actual application, and also introduces the recently occurred line break protection technologies and their applications. The study results can provide useful reference for rational design, correct construction and effective maintenance of line break protection of gas over oil actuator of natural gas pipelines in China.