The invention discloses 
a DNA electrochemical sensor based on target 
DNA repetitive sequence self enhancement and amplification 
signal. A 
signal probe is designed by a 
repetitive sequence clip of a detected target chain, thus, the volume of the 
signal probes combined with the target sequence is increased, and a compound is formed, when a capture probe on 
electrode surface is hybridized with the target sequence, the amplified signal probe is combined with the 
electrode surface, under the affinity function between the 
biotin treated by end labeling of the signal probe and the 
avidin modified on the 
horseradish peroxidase, multiple enzymes are combined with a 'sandwich' structure, finally, under the efficient catalytic action of the enzymes, H2O2 is catalyzed to oxidize the TMB, the oxidative product generates an amplified reduction current 
signal on the 
electrode, and the concentration of the target 
DNA is judged according to the magnitude of the current signal. In the experiment, based on the characteristics of self enhancement and amplification signal of the target chain of the 
repetitive sequence, the target chain with two sections of 
repetitive sequences is detected, and the method is high in sensitivity.