Abstract: The improved quantum molecular dynamics (ImQMD) model and ImQMD model incorporated with the microscopic potential energy surface (ImQMD+MicPES) are employed to simulate the multinucleon transfer reaction of ^238\mathrmU + ^238\mathrmU at the incident energy of 7.35\;\mathrmMeV per nucleon. Compared with the calculations using ImQMD model, the production cross sections for secondary products with mass numbers ranging from 190 to 230 are overall reduced with considering the microscopic potential energy surface of two-dimensional collective coordinates (i.e., the elongation coordinate Q_20^ and the mass asymmetry coordinate Q_30^ ). However, with the microscopic potential energy surface with three-dimensional collective coordinates (i.e., the elongation coordinate Q_20^ , the mass asymmetry coordinate Q_30^ , and the neck coordinate Q_40^ ), the production cross sections for secondary products with mass numbers below 200 are further decreased, while those for mass numbers above 200 are enhanced, resulting in an overall better reproduction of the experimentally measured mass distribution. The calculated results indicate that the neck degree of freedom play an important role in the consideration of shell effects in the ^238\mathrmU + ^238\mathrmU reaction, and shell effects significantly influence both the multinucleon transfer process and the angular distribution of reaction products.