The ultra-high-energy(UHE) gamma-ray source 1LHAASO J0007+7303u is positionally associated with the composite SNR CTA1 that is located at high Galactic Latitude b≈10.5°.This provides a rare opportunity to spatially resolve the component of the pulsar wind nebula(PWN) and supernova remnant(SNR) at UHE.This paper conducted a dedicated data analysis of 1LHAASO J0007+7303u using the data collected from December 2019 to July 2023.This source is well detected with significances of 21σ and 17σ at 8-100 TeV and100 TeV,respectively.The corresponding extensions are determined to be 0.23°±0.03° and 0.17°±0.03°.The emission is proposed to originate from the relativistic electrons accelerated within the PWN of PSR J0007+7303.The energy spectrum is well described by a power-law with an exponential cutoff function dN/dE=(42.4±4.1)(E/20TeV)~(-2.31+0.11) exp(-E/(110±25Tev)) TeV-1 cm~(-2) s~(-1) in the energy range from 8 to 300 TeV,implying a steady-state parent electron spectrum dN_e/dE_e ∝(E_e/100TeV)~(-3.13±0.16) exp[(-E_e/(373±70TeV))~2] at energies above≈50 TeV.The cutoff energy of the electron spectrum is roughly equal to the expected current maximum energy of particles accelerated at the PWN terminal shock.Combining the X-ray and gamma-ray emission,the current space-averaged magnetic field can be limited to≈4.5 μG.To satisfy the multi-wavelength spectrum and the y-ray extensions,the transport of relativistic particles within the PWN is likely dominated by the advection process under the free-expansion phase assumption.