The orthogonal wavelet packet analysis method was applied on dynamics recognition of fractional order system. Firstly, the signal’s band was split up into proper levels and the sub-signals were gained, which correspond to each frequency band according to the average period of the time-series. Then, by analysis of sub-frequency band power distribution in the signal’s total power, the chaos in the related signal can be easily identifed . Finally, by taking the controlled fractional order Chen’s system as an illustration, the results obtained by this procedure agree with those by power spectrum method. So this new method can be used for dynamics recognition in fractional order systems.