A data slicer capable of dynamically adjusting a slice level according to a wobble signal retrieved from a DVD-R/RW disc. The data slicer has a peak hold circuit for generating a first output signal according to positive peaks of the wobble signal, a bottom hold circuit for generating a second output signal according to negative peaks of the first output signal, a bias circuit for utilizing a bias voltage to raise voltage levels of the second output signal to generate the slice level, and a comparator for comparing the wobble signal with the slice level to generate corresponding square wave signal.