The present paper deals with evaluation of petro-physical parameters of Hawaz Formation at J oil field, Concession NC186 in Murzuq basin through the analysis of well-log data available for ten exploratory wells, distributed in J oil field. A comprehensive formation evaluation has been applied through numbers of cross-plots and using their output parameters as input data for interactive petro-physics software (IP) in order to evaluate the lithological constituents and fluid saturations. The litho-saturation cross-plot indicated that the Hawaz Formation consists of sandstones with few shale. These sandstones are generally fine to very fine grains but occasionally coarse to very coarse grained. Generally coursing upward sequence is indicated. The litho-saturation cross-plots also illustrated that horizon H4 and H5 are the main reservoirs in Hawaz formation