The characteristics of high noise and strong transients of power signals in remote distribution network in China cause great disturbance to phasor measurement, and it is of great significance for the stability and reliability of power grid to obtain the phasor information of power signal reliably, quickly and precisely under the noise environment. This paper puts forward a kind of power signal synchronous phasor tracking algorithm based on the adaptive strong tracking unscented Kalman filter (ASTUKF). A novel system state decision variables is built according to the characteristics of the probability distribution of the new interest to determine whether a system mutated, and the weakening factor adaptive algorithm is proposed based on the theory of STUKF algorithm. The fundamental phasor state space modeling is established based on synchronous phasor ASTUKF tracking algorithm. Experimental results show that the proposed ASTUKF algorithm has good mutation detection ability and can track mutations quickly and accurately.