Underground water quality sensors

The invention discloses an underground water quality sensor comprising a cable, a fixing rack, a sensor main rod, and a probe. One end of the sensor main rod is connected with the cable, and the fixing rack is disposed between the cable and the sensor main rod, and in addition, the other end of the sensor main rod is provided with a probe. The probe comprises a positive pole and a negative pole, and the upper end of the probe is provided with a hardness alarming device, a PH value alarming device, a salinity alarming device, a water level alarming device, and a thermistor. During the use of the underground water quality sensor, the thermistor can be used for a certain temperature compensation automatically, and therefore the accurate analysis can be facilitated. The PH value alarming device and the hardness alarming device can be used for the monitoring of the PH value and the hardness of the water quality, and the salinity alarming device and the water level alarming device can be used for the detection of the salinity and the water level of the water quality. By using the underground water quality sensor, the different parameters of the underground water quality can be monitored accurately and effectively in a real-time manner.