  We have studied the variability of \object{S5 0716+714} at radio 15 GHz and
$\gamma$-ray band using three different methods. A possible periodicity of
$P_{15 GHz}=266.0\pm11.5$ and $P_{\gamma}=344.0\pm16.4$ days are obtained for
radio 15 GHz and $\gamma$-ray light curves, respectively. The variability may
be related to the intrinsically emission mechanism. The difference between the
variability timescales of radio 15 GHz and $\gamma$-ray may be due to that the
emission of radio 15 GHz is produced via the synchrotron process, while the
$\gamma$-ray is produced by both the SSC and EC processes.
