  In this paper, we introduce a self-consistent mean field approximation to
study the QCD phase transition and the structure of hybrid stars within the
framework of NJL model. In our practice, a phenomenological parameter $\alpha$
is introduced, which reflects the weights of "direct" channel and "exchange"
channel under a finite chemical potential. The mass-radius relation is obtained
by solving the Tolman-Oppenheimer-Volkoff equation using a crossover equation
of state (EOS). We calculate the density distribution in a two solar-mass
hybrid star to show the effects of different parameters. We also calculate the
tidal Love number $k_2$ and the deformability $(\Lambda)$. It is found that the
stiffness of the EOS increases with $\alpha $, which allows us to obtain a
hybrid star with a maximum mass of 2.40 solar-mass through our model. The
observation of over 2.06 solar-mass neutron stars may indicates that the chiral
transition may be a crossover on the whole $T-\mu$ plane.
