The invention relates to a method and an apparatus for compensating clock bias, wherein the apparatus for compensating clock bias which is applied to a Global Navigation Satellite System (GNSS) receiver comprises a clock source for providing a reference time which has a clock bias to be compensated and a processing module which is coupled to the clock source for deriving at least one clock drifting value. The clock drifting value contains a first clock drifting value corresponding to a first time point. The clock bias is calculated according to the at least one clock drifting time and at least one time section, wherein the at least one time section is a time period between the first time point and a special time point after the first time point. The method and the apparatus provided by the invention can derive the time information and obviously decrease the first locating time.