In this study,a novel electrochemical sensor was constructed for the detection of DNA methylation,with a DNA tetrahedral nanostructure probe(TSP) as capture probe and horseradish peroxidase-labeled IgG antibody bound to the surface of gold nanoparticles (AuNPs-IgG-HRP) as a signal molecule.After being assembled into TSP by the one step thermal denaturation method,the probe was fixed on the surface of AuNPs/AuE electrode through Au-S bond.Experienced the target DNA hybridization,5-methylcytosine (5-mc) antibody and AuNPs-IgG-HRP conjugation,the electrochemical signal was obtained by differential pulse voltammetry(DPV).The construction process of the modified electrode was characterized by cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS).Effects of hybridization time,5-mc antibody concentration,addition volume of IgG-HRP,concentrations of hydroquinone(HQ) and hydrogen peroxide(H2O2) on the sensor were explored.Under the optimal conditions,the biosensor exhibited a good linear response toward the methylated DNA in the range of 1.0×10-15-1.0×10-10 mol/L,with a detection limit (S/N=3) of 4.4×10-16 mol/L.The biosensor could provide a new method for the detection of DNA methylation with good selectivity and stability.