  We studied the PeVatron nature of the pulsar wind nebula G75.2+0.1
("Dragonfly") as part of our NuSTAR observational campaign of energetic PWNe.
The Dragonfly is spatially coincident with LHAASO J2018+3651 whose maximum
photon energy is 0.27 PeV. We detected a compact (radius 1') inner nebula of
the Dragonfly without a spectral break in 3 $-$ 20 keV using NuSTAR. A joint
analysis of the inner nebula with the archival Chandra and XMM-Newton
observations yields a power-law spectrum with $\Gamma=1.49\pm0.03$. Synchrotron
burnoff is observed from the shrinkage of the NuSTAR nebula at higher energies,
from which we infer the magnetic field in the inner nebula of 24 $\mu$G at 3.5
kpc. Our analysis of archival XMM data and 13 years of Fermi-LAT data confirms
the detection of an extended (~10') outer nebula in 2 $-$ 6 keV
($\Gamma=1.82\pm0.03$) and non-detection of a GeV nebula, respectively. Using
the VLA, XMM, and HAWC data, we modeled a multi-wavelength spectral energy
distribution of the Dragonfly as a leptonic PeVatron. The maximum injected
particle energy of 1.4 PeV from our model suggests that the Dragonfly is likely
a PeVatron. Our model prediction of the low magnetic field (2.7 $\mu$G) in the
outer nebula and recent interaction with the host supernova remnant's reverse
shock (4 kyrs ago) align with common features of PeVatron PWNe. The origin of
its highly asymmetric morphology, pulsar proper motion, PWN-SNR interaction,
and source distance will require further investigations in the future including
a multi-wavelength study using radio, X-ray, and gamma-ray observations.
