The invention discloses an electrochemical detector based on an audio port of a smartphone for power supply and relates to the technical field of electrochemical detection. A power module gains energy from the audio port of a smartphone. The detector itself needs no power supply such that size and cost of the detector are effectively reduced. Meanwhile, both-way communication between the smartphone and the electrochemical detector is realized through a right channel and a microphone of the phone's audio port. Detection, calculation, control and display and other functions of electrochemical detection modules can be realized through the smartphone. Thus, the circuit of the electrochemical detection modules is simplified. The electrochemical detector is flexible to use and has a wide range of coverage and can be used on most places and occasions.