  In 2015 October, the Be/X-ray binary 4U 0115+63 underwent a type II outburst,
reaching an X-ray luminosity of $\sim$ {\DP{38}\es}. During the outburst,
Nuclear Spectroscopic Telescope Array ({\it NuSTAR}) performed two Target of
Opportunity observations. Using the broad-band spectra from {\it NuSTAR}
(3$-$79 keV), we have detected multiple cyclotron lines of the source, i.e.,
$\sim$ 12, 16, 22 and 33/35 keV. Obviously, the 16 keV line is not a harmonic
component of the 12 keV line. As described by the phase-dependent equivalent
widths of these cyclotron lines, the 16 keV and 12 keV lines are two different
fundamental lines. In our work, we apply the two-poles cyclotron line model to
the observation, i.e., the two line sets are formed at the same altitude
($\sim$ 0.2 km over the NS surface) of different magnetic poles, with $\sim$
{1.1\TDP{12}} and {1.4\TDP{12}} G in two poles, respectively.
