The present invention relates to a system, and a method for time synchronization with low power consumption and high accuracy. The system comprises a plurality of devices for time synchronization. Each device comprises a GPS receiver, a microprocessor, and an oscillator. The microprocessor generates a drift per second according to the difference between the PPS signal and the clock signal, and calibrates the clock signal constantly according to drift per second. The GPS receiver is turned off when the drift per second is obtained, and then is turned on after a pre-determined time period for updating the drift per second.