The invention discloses a special low-cost dissolved oxygen sensor for aquaculture. The special low-cost dissolved oxygen sensor comprises an outlet cable, a sensor main body, a sensor electrode core, a millstone, a push rod motor, a protection cover and a connection piece, wherein the sensor main body comprises an analog-digital conversion circuit, a signal amplification circuit, a filter circuit and a microcontroller module which are connected with one another in sequence; the sensor electrode core comprises an anode and a cathode; and the sensor main body also comprises a clock module, an input setting module and a data storage module. The work period of the push rod motor can be preset, the service life of the sensor electrode core is prolonged, data is stored by the data storage module in real time, and thus data loss caused by sensor failure is avoided. The surface of the sensor electrode core can be cleaned automatically, the measurement precision is high, and the measurement precision is not influenced by water pollution and water flow speed. According to the specific implementation manner, the dissolved oxygen sensor has the advantages of simple structure, reasonable arrangement, low manufacture cost, and the like.