Floquet engineering appears as a new protocol for designing topological states of matter, and features anomalous edge modes pinned at quasi-energyπ/T with vanished topological index. We propose how to predict the anomalous edge modes via the bulk Hamiltonian in frequency space, and use Zak phase to quantitatively index the topological properties. The above methods are clarified by the example of time periodic Kitaev chain with chemical potential of harmonic driving and pulse driving, and topological phase transitions are manifested at different driving frequencies.