The invention discloses a sensor based on a black phosphorus electrode and a preparation method of the sensor. The preparation method comprises the following steps: 1, preparing black phosphorus; 2, dipping the black phosphorus with an organic solvent; 3, preparing the black phosphorus electrode; and 4, preparing the sensor. According to the sensor based on the black phosphorus electrode, the direct contact between oxygen or oxide and black phosphorus can be prevented, the excellent performances of black phosphorus in the electrochemical detection are exerted, a foundation is laid for the application of the black phosphorus electrode and the sensor based on the black phosphorus electrode, and the sensor and the preparation method thereof have a wide application prospect.