In Global Navigation Satellite System (GNSS) receiver,ionospheric scintillation may lead huge tracking error and frequent cycle clips to the carrier phase tracking loop.When strong scintillation,the phase lock loop (PLL) of receiver may even lose lock.Although the frequency lock loop (FLL) is insensitive to the ionospheric scintillation,the tracking accuracy is poor which is insufficient for most GNSS applications.In this paper,we propose an improved adaptive Kalman filter based carrier phase locking loop for the scintillated signal tracking.In the loop,the signal amplitude is added in the state vector of the Kalman filter.By calculating the statistic result of the amplitude variance,the amplitude is adaptively estimated.At the same time,the phase discriminator is normalized by the amplitude estimation results.The Kalman filter is redesigned based on the new structure so as to improve the stability of the loop and reduce the effects of amplitude attenuation and phase jitter on the loop.Simulation is carried out based on the ionospheric scintillation data obtained according to the A.J.Stanford model.The results show that the proposed loop can keep working in the continuously moderate and instantaneous strong ionosphere scintillation with less cycle clips.