Orthogonal Frequency Division Multiplexing (OFDM) is considered as an important technique for future wireless communications. In addition, OFDM has a better performance at inter symbol interference (ISI). One of the major disadvantages of the multi-carrier modulation is about the sensitivity of the performance to a frequency offset. In this paper, we propose an iterative algorithm of frequency offset estimation for the OFDM system. The fundamental algorithm of our iterative algorithm is the frequency pilot aided algorithm. When we get a result with the fundamental algorithm every time, we use the result to estimate for a second time. The algorithm we proposed does not require some additional pilots or changing the data structure of the fundamental algorithm.