  In this paper, we presented a detailed timing analysis of a prominent
outburst of 4U 0115+63 detected by \textit{Insight}-HXMT in 2017 August. The
spin period of the neutron star was determined to be $3.61398\pm 0.00002$ s at
MJD 57978. We measured the period variability and extract the orbital elements
of the binary system. The angle of periastron evolved with a rate of
$0.048\pm0.003$ $yr^{-1}$. The light curves are folded to sketch the pulse
profiles in different energy ranges. A multi-peak structure in 1-10 keV is
clearly illustrated. We introduced wavelet analysis into our data analysis
procedures to study QPO signals and perform a detailed wavelet analysis in many
different energy ranges. Through the wavelet spectra, we report the discovery
of a QPO at the frequency $\sim 10$ mHz. In addition, the X-ray light curves
showed multiple QPOs in the period of $\sim 16-32 $ s and $\sim 67- 200 $ s. We
found that the $\sim100$ s QPO was significant in most of the observations and
energies. There exist positive relations between X-ray luminosity and their
Q-factors and S-factors, while the QPO periods have no correlation with X-ray
luminosity. In wavelet phase maps, we found that the pulse phase of $\sim 67-
200 $ s QPO drifting frequently while the $\sim 16-32 $ s QPO scarcely
drifting. The dissipation of oscillations from high energy to low energy was
also observed. These features of QPOs in 4U 0115+63 provide new challenge to
our understanding of their physical origins.
