  In this paper, we are concerned with the following type of fractional
problems:
  $$
  \begin{cases}\dis
  (-\Delta)^{s} u-\mu\frac{u}{|x|^{2s}}-\lambda u=|u|^{2^*_{s}-2}u+f(x,u),
&\text{in} \Omega,\ \
  \,
  u=0\,&\text{in} \R^N\backslash\Omega
  \end{cases}
  \eqno {(*)} $$
  where $s\in (0,1)$, $2^*_{s}=2N/(N-2s)$ is the critical Sobolev exponent,
$f(x,u)$ is a lower order perturbation of critical Sobolev nonlinearity. We
obtain the existence of the solution for (*) through variational methods. In
particular we derive a Br\'ezis-Nirenberg type result when $f(x,u)=0$.
