The invention discloses a high-precision real-time clock chip which comprises a clock timing module, an I2C interface module, an alarming and periodic interrupt module, a power management module and a digital temperature compensation crystal oscillator; the clock timing module comprises a second register, a minute register, an hour register, a week register, a day register, a moon register, a year register and a square wave output control register; the hour register, the day register, the moon register and the year register are connected with a combinational logic circuit; and the digital temperature compensation crystal oscillator comprises a temperature sensor, an analogue digital converter, a storage cell, a capacitor array and a crystal oscillator. The high-precision real-time clock chip provided by the invention can be repaired and adjusted within an industrial temperature range, can achieve self calibration, greatly improves the accuracy of RTC, meanwhile the problem of electromagnetic interference on macroscopic circuit wiring can be solved, and more I / O resources of the main system are saved.