The　range　of　the　frequency　offset　estimation　algorithms　using　pilots　only　proposed　in　earlier　papers　is　limited　unless　initial　acquisition　is　assisted.　So　in　this　paper,　we　propose　a　new,　semi-blind　algorithm　based　on　pilots　and　cyclostationarity.　First,　the　cyclostationarity　of　the　OFDM　signal　which　contains　pilots　is　proved.　Then　the　algorithm　for　estimating　the　carrier　frequency　offset　based　on　the　cyclic　autocorrelation　function　of　the　cyclostationary　signal　is　proposed.　Compared　with　those　algorithms　using　pilots　directly,　this　new　algorithm　can　get　larger　frequency　offset　estimation　up　to　half　of　the　bandwidth　of　the　OFDM　system　without　initial　acquisition,　and　the　symbol　timing　can　be　estimated　as　well.