A novel DNA sensor was designed for the determination of breast cancer genes based on three electrochemical probes,the negative electrochemical probe ［Fe(CN)6］3-/4-,methylene blue and the positive electrochemical probe［Ru(NH3)6］3+.The breast cancer genes DNA sensor was fabricated by immobilizing a breast cancer gene ssDNA onto the surface of gold nanoparticles-multi-walled carbon nanotubes(MWCNT)-Nafion modified gold electrode through adsorption,and characterized by cyclic voltammetry,differential pulse voltammetry and electrochemical impedance method.Under the optimized conditions,in 5 mmol/L K3［Fe(CN)6］ -5 mmol/L K4［Fe(CN)6］(pH=7.4) solution,the electrochemical current response of the sensor was linear with the logarithm of the breast cancer gene concentration in range of 0.1-500.0 nmol/L,with a detection limit(S/N=3) of 0.03 nmol/L.While using methylene blue as the electrochemical probe,the electrochemical current response was linear with concentration of breast cancer gene in range of 1.0-500.0 nmol/L,and the detection limit was 0.3 nmol/L.Based on the different binding ability of ［Ru(NH3)6］3+with ssDNA and dsDNA,the current response of the sensor using ［Ru(NH3)6］3+ as the probe was still linear with concentration of breast cancer gene in the range of 1.0-500.0 nmol/L.The detection limit was 0.3 nmol/L.Among three kinds of electrochemical probes,［Fe(CN)6］3-/4- probe had the lowest detection limit and the widest linear range for the detection of breast cancer gene.