This paper presents a novel frequency offset estimation algorithm based on the linear regression. Frequency offset estimation is converted to the estimation of argument increment which satisfy the linear relationship. The algorithm correlates the signal received with local PN sequences, and then calculates the frequency offset based on the linear regression of arguments of the correlation results. Simulations indicate that the algorithm has advantages of accurate estimation over multi-path channels and excellent performance of channel noise suppression. The accuracy of the algorithm is not sensitive to frequency offset in the effective range. In addition, the algorithm reduces system resources by sharing the same PN sequence and correlation results with PN synchronization and can be easily implemented.