Collinear holography is a technology for ultra-high density and ultra-high speed optical storage system. The reflective disc structure can reflect the reconstructed image back to the same objective lens. As this reason, the system structure can be simplitied which is compatible with existing storage disc systems, like CD and DVD. Servo technologies, which are applied in the optical disc, can precisely maintain the distance and the relative position of the objective lens and the disc, and the holograms can be recorded and reconstructed in a disc accurately. Furthermore a vibration isolator is not necessary any more. The existing essential issues for practicality in conventional 2-axis holography are discussed firstly. And then, collinear holography is introduced and the recording and reconstructing process is demonstrated. Tilt margin and wavelength margin of this system are analyzed from the experimental results. it is proved that the low cost and compactable device can be manufactured theoretically.