Abstract: Over the past few years, OTF integer ambiguity resolution for GPS has proven to be successful for short baseline (<20 km).However, the challenge still exists when the baseline is long.This paper provides a method to process the kinematic GPS data in which the distance is hundreds of kilometers between the reference station and the mobile receiver.The method is to estimate satellite clock offsets using IGS precise ephemeris and the observation data of the IGS tracking stations every epoch, then transfer them to the mobile receiver for positioning.The method is used to process GPS data of the Arctic, and the results show that the precision in the horizontal component is better than 1meter (1σ) and the deduced velocity of the ice sheet is 420 meters per hour.