Abstract: Precise synchronization can be achieved by fitting phase discrimination curve exploiting Least Squares (LS). However, this method not only has very high requirement of coarse synchronization, but also can not counteract frequency- offset effectively. It is analyzed and proved that the measured value of LS is between zero and real value as coarse synchronization error is between the earlier and later chip. Accordingly a precise synchronization method based on iterative least squares is proposed and a modulus of split correlation strategy is also introduced in this paper to counteract frequency-offset. Theoretical analysis shows that this method can outstandingly eliminate influence of noise as well as frequency-offset with short segments. Besides its strong anti frequency-offset and noise capability, the proposed method still has very high measurement precision as the error of coarse synchronization covers the earlier and later half chip according to simulation results.