A novel MXene-based nanocomposite (MXene/DNA/Pd/Pt) is synthesized end applied for the development of sensitive dopamine (DA) sensors. MXene nanosheets act as conductive matrix for Pd/Pt nanoparticles loading, and DNA is adsorbed on MXene surface through aromatic hydrophobic bases to induce the In-situ growth of PdNPs and Pd/Pt nanoparticles. The results reveal that DNA plays vital roles in the formation of the nano composites, which not only favors the dispersion of Ti3C2 nanosheets, but also facilitates the even growth of PdNPs and Pd/Pt nanoparticles. The deposition of Pd/Pt nanoparticles onto Ti3C2 nanosheets efficiently enhances the electrocatalytic activity of the nanocomposites towards DA. The constructed sensor exhibited linear amperometric response in the DA concentration range of 0.2-1000 mu M with a lower detection limit of 30 nM (S/ N = 3) and high selectivity against ascorbic acid (AA), uric acid (UA) and glucose (Girl). The successful determination of DA in human serum samples further verifies the potential application of the constructed sensors.