  We present the formation and eruption of a sigmoidal filament driven by
rotating network magnetic fields (RNFs) near the center of the solar disk,
which was observed by the one-meter aperture New Vacuum Solar Telescope (NVST)
at Fuxian Solar Observatory (FSO) on 2018 July 12. Counterclockwise RNFs twist
two small-scale filaments at their northeastern foot-point region, giving a
rotation of nearly 200 degree within about 140 minutes. The motion of the RNF
has a tendency to accelerate at first and then decelerate obviously, as the
average rotation speed increased from 10 to 150 ,and then slowed down to 50 .
Coalescence then occurs between filaments F1 and F2. Meanwhile the fine
structures in the southwestern region of the filament was involved in another
interaction of coalescence. The subsequent EUV brightening due to plasma
heating is observed in the two interaction regions. These interacting
structures, including F1, F2 and the fine structures in the southwestern
region, eventually evolve into a larger-scale sigmoidal filament twisted in the
same direction as the RNFs gave. The twist of the sigmoidal filament has
exceeded 4{\pi} and the filament erupted finally. The motion of the sigmoidal
filament keeps uniform until a nearby jet collides, causing the filament to
erupt faster. These results provide evidence that RNF plays an important role
in the formation and eruption of the sigmoidal filament. The phenomena also
suggests that the kink instability is the trigger mechanism for the filament
eruption.
