Abstract: To solve problems of time synchronization and monitoring of parking lot, an NTP-based time synchronization system for the parking lot was designed to synchronize and trace the time of the parking lot to UTC (NIM), and the filtering algorithm of NTP was optimized to reduce the impact caused by network link asymmetry, and the average time deviation after synchronization is reduced by 2.62 ms. The system runs on μC/OS real-time operating system, adopts NTP to synchronize time to time standard in near real-time through 4G wireless transmission, then transmits the synchronized time to the parking lot timing and charging system through bus or Ethernet, and uploads the time deviation to the monitoring platform at the same time, which effectively solves the time synchronization problem of parking lot timing and charging system.