  We employ a new self-consistent mean field approximation of NJL model, which
introduces a free parameter $\alpha$ ($\alpha$ reflects the weight of different
interaction channels), to study the effects of the chiral chemical potential
$\mu_5$ on QCD phase structure, especially the location of the QCD critical end
point (CEP). We find that, at a high temperature, the critical temperature of
QCD phase transition smoothly increases with $\mu_5$ at the beginning, and then
decreases rapidly. At low temperature and high baryon density region, the
increase of the chiral chemical potential will reduce the critical chemical
potential of phase transition. The temperature of the CEP shows a non-monotonic
dependence on the chiral chemical potential with a long plateau around the
maximum. At $\mu_5=0$, we found that the CEP will disappear when the $\alpha$
value is larger than 0.71 and will reappear when the $\mu_5$ increases. This
study is important for exploring the QCD phase structure and the location of
CEP in chiral imbalanced systems.
