  BL Lac objects are the best candidates to study the jet properties since
their spectral energy distributions (SEDs) are less contaminated by the
emission from the accretion disk and external Compton processes. We compile the
broadband SEDs observed with Fermi/LAT and other instruments from literature
for 24 TeV BL Lac objects. Two SEDs, which are identified as a low or high
state according to its flux density at 1 TeV, are available for each of ten
objects. These SEDs can be explained well with the
synchrotron+synchrotron-self-Compton model. We constrain the magnetic filed
strength B and the Doppler factor delta of the radiation region by
incorporating the chi^{2}-minimization technique and the gamma-ray transparency
condition. Twenty-four out of the 34 SEDs can constrain B and delta in 1 sigma
significance level and others only present the limits for both B and delta. The
typical values of $B$ and delta are 0.1 ~ 0.6 G and 10 ~ 35, respectively. The
derived values of gamma_b are significantly different among sources and even
among the low and high states of a given source. Prominent flux variations with
a clear spectral shift are observed and a tentative correlation between the
ratio of the flux density at 1 TeV and the ratio of gamma_b in the low and high
states is presented, likely indicating that the relativistic shocks for the
electron acceleration may be responsible for the flux variations and the
spectral shift. A weak anti-correlation between the jet power and the mass of
the central black hole is observed, i.e., P_{jet} propto M^{-1}_{BH}, which
disfavors the scenario of a pure accretion-driven jet. Implications for the
blazar sequence and the intergalactic magnetic field from our results are also
briefly discussed.
