Vibrio parahaemolyticus is one of the most prevalent foodborne pathogen,which can cause gastroenteritis.In this paper,a label-free detection system for virulence gene of V.parahaemolyticus (tdh) based on gold electrodes was described.A single-stranded 20mer oligonucleotide (ssDNA) was immobilized via a thiol linker on gold disk electrodes and served as probe DNA,residual binding places were filled with 6-mercapto-1-hexanol (MCH).The probe DNA could hybridize with complementary or non-complementary target ssDNA,using Hoechst 33258 as redox indicator.The changes in the anodic current signal of Hoechst 33258 at 0.50 V was monitored between complementary and non-complementary DNA in connection with linear sweep voltammetry (LSV).Additionally,detection of single base mismatch was also detected.The peak currents after hybridization with these three target DNA were 6.84 μA,3.09 μA and 4.34 μA,respectively,which was shown that the sensor had a high selectivity.In the presence and absence of MCH,the anodic current signal was 2.25 μA and 6.21 μA,considering that MCH could effectively displaced adsorbed ssDNA from the gold surface.The difference of current between before and after hybridization with complementary DNA was about 4.8 μA when the salt concentration was 0.1 M,which was wider compared with other conditions.A target DNA detection limit of 0.025 μM was achieved without signal amplification.