By employing the full potential augmented plane wave and local orbital method (APW+lO), we studied some possible hydrogen-related defect sites in ZnO. In view of the calculated defect formation energy, the most possible defect site should inhabit BC∥ local structure position. But the calculated local vibrational modes (LVMs) of the defect sites, when compared with the infrared absorption result, leads to the conclusion that the hydrogen-related defect sites in ZnO can inhabit both BC∥ and ABo∥ local structure positions.