MXene is an emerging two-dimensional high-performance electrode material with various surface terminations during the preparation process, where the influence of these surface functional groups on the catalytic performance of MXene supported metal nanocatalysts receives only limited attentions. In this work, the hydrogen evolution reaction (HER) performance of Nb2CTx (T represents different functional groups) supported Pd nanocatalysts are studied via experiment and theoretical calculation. Different reagents are adopted to treat the Nb2C followed by loading Pd nanoparticles (NPs) in experiment. The Pd/Nb2C-HF exhibits outstanding HER performance compared to the Pd/Nb2C-H2SO4 and Pd/Nb2C-HNO3. The density functional theory calculations reveal that the modulation of electronic distribution of Pd NPs is observed by varying the surface functional groups and thus results in different HER performances. The F functional group in the Pd/Nb2C-HF is beneficial to decreasing the charge-transfer resistance and weakening the hydrogen adsorption. This study opens up a new route for designing electrocatalysts via changing surface terminations on MXene materials with enhanced HER performance.