  We estimate the intrinsic luminosities and synchrotron peak frequency using
the derived Doppler factor for a sample of 170 BL Lac objects, of which the
synchrotron peak frequency are derived by fitting the SED constructed with the
collected multi-band data from literatures. We find that the debeamed radio and
optical core luminosities follow the same correlation found for FR I radio
galaxies, which is in support of the unification of the BL Lac objects and the
FR I galaxies based on orientation. For the debeamed luminosity at synchrotron
peak frequency, we find a significant positive correlation between the
luminosity and intrinsic synchrotron peak frequency. This implies that the more
powerful sources may have the majority of jet emission at higher frequency. At
synchrotron peak frequency, the intrinsic luminosity and black hole mass show
strong positive correlation, while mild correlation is found in the case of jet
power, indicating that the more powerful sources may have heavier black hole.
