A method and apparatus for obtaining Global navigation Satellite System (GNSS) time in a GNSS receiver are provided. The following steps are included: obtaining a time relationship between a first clock signal and the received GNSS time; obtaining a first clock value of a second clock signal and an first associated clock value of the first clock signal at a first time point; calculating a first GNSS time corresponding to the first clock value of the second clock signal according to the first associated clock value and the time relationship; obtaining a second clock value of the second clock signal and an second associated clock value of the first clock signal at a second time point; and calculating a second GNSS time corresponding to the second associated clock value, according to the first GNSS time, the first clock value and the second clock value of the second clock signal.