HESS J1303-631 is an extended TeV pulsar wind nebula powered by the pulsar PSR J1301-6305 detected with the High Energy Stereoscopic System. We present an analysis of the GeV γ-ray region of HESS J1303-631 with about 14 yr of Fermi Large Area Telescope data. The GeV γ-ray emission, coincident with the very-high-energy source, has a photon index of 1.69 ± 0.09 in 10–500 GeV band, and the GeV morphology has an extension to the same direction as indicated in the TeV band. Moreover, the observed multi-wavelength spectral energy distribution of the nebula is studied with a one-zone time-dependent leptonic model, in which the electrons/positrons injected into the nebula are assumed to have a broken power-law spectrum. The result indicates that the multi-wavelength non-thermal emission can be well reproduced via synchrotron radiation and inverse Compton scattering of the particles.