Abstract:    Locata system is a newtype of high-precision foundation positioning system. It can be not only seamlessly connected with the existing Global Satellite Navigation System (GNSS), but also provide the positioning service independently when the satellite signal fails. The positioning accuracy of Locata system can reach centimeter level, and its key technology is high-precision (nanosecond level) time synchronization technology. In this paper, by analyzing the positioning principle of Locata system and studying its unique time synchronization technology, the time synchronization mechanism of the system and its technical implementing scheme are described in detail, and the specific process and steps for time synchronization are also given. This study can provide a reference for China's development of foundation pseudo satellite positioning system.