Ultrasensitive DNA electrochemical detection method, reagent and system

The invention provides an ultrasensitive DNA electrochemical detection method which comprises the following steps: fixing a DNA capture probe on a working electrode of a DNA electrochemical sensor; fixing MCH on the working electrode fixedly provided with the DNA capture probe; additionally arranging a to-be-detected DNA sample and a DNA signal probe to the working electrode for performing hybrid treatment; and detecting an electrochemical signal of the working electrode subjected to the hybrid treatment. According to the ultrasensitive DNA electrochemical detection method disclosed by the invention, the working electrode is closed by using MCH (6-mercapto-1-hexanol), a number of non-target DNA signals and background signals can be shielded, a sensor noise signal is reduced, and the sensitivity of the sensor is improved.