Mercury is a highly toxic element that is widely present in all types of environmental media and can accumulate in living organisms. Prolonged exposure to high levels of mercury can lead to brain damage and death, so the detection of mercury is of great importance. In this study, a cost-effective and easy-to-operate electrochemical sensing method was successfully developed based on an amino-functionalized titanium-based MXene (NH2-Ti3C2Tx) for the rapid and selective detection of Hg2+ that could have a coordination effect with the -NH2 group of NH2-Ti3C2Tx to promote the efficient accumulation of Hg2+. In this strategy, the NH2-Ti3C2Tx was first modified on glassy carbon electrodes (GCE) to fabricate the electrochemical sensor. Benefiting from the excellent electrical conductivity, abundant active sites, and strong adsorption capacity performance of the NH2-Ti3C2Tx, the NH2-Ti3C2Tx modified GCE (NH2-Ti3C2Tx/GCE) exhibited satisfactory selectivity and enhanced square wave anodic stripping voltammetry (SWASV) measurement for the rapid detection of trace amounts of Hg2+ in aqueous solutions. The electrochemical sensor was found to be capable of detecting Hg2+ with a low detection limit of 8.27 nmol L-1 and a linear range of 0.5 μmol L-1 to 50 μmol L-1. The response time of the electrochemical sensing method was 308 s. In addition, the electrochemical sensing method has good selectivity, repeatability and stability, and multiple heavy metal ions have no effect on its detection, with repeatability and stability RSDs of 1.68% and 1.43%, respectively. Furthermore, the analysis of practical water samples demonstrated that the developed method was highly practical for the actual determination of Hg2+ with recoveries in the range of 99.22-101.90%.