  We compiled a sample of 60 quasars with spectroscopy on at least six epochs
from the Sloan Digital Sky Survey (SDSS) to study the variabilities of the
spectral shape, the continuum and the emission lines luminosity. In this paper,
we present the results of SDSS J030639.57+000343.1. We found a strong
anti-correlation between the continuum luminosity at $5100 \AA$ and the
spectral index, implying a bluer-when-brighter trend. The luminosity of the
broad $\rm H_\alpha$ line is proportion to the continuum luminosity at $5100
\AA$. Correspondingly, we did not find strong correlation between the
equivalent width of broad $\rm H\alpha$ and the continuum luminosity, i.e. no
baldwin effect of broad $\rm H\alpha$ in this source.
