  We study the level statistics of one-dimensional Schr\"odinger operator with
random potential decaying like $x^{-\alpha}$ at infinity. We consider the point
process $\xi_L$ consisting of the rescaled eigenvalues and show that : (i)(ac
spectrum case) for $\alpha > \frac 12$, $\xi_L$ converges to a clock process,
and the fluctuation of the eigenvalue spacing converges to Gaussian.
(ii)(critical case) for $\alpha = \frac 12$, $\xi_L$ converges to the limit of
the circular $\beta$-ensemble.
