Abstract: Electrochemical sensing technology has become a research hotspot in the field of analytical chemistry due to its low cost, high sensitivity, good selectivity, and fast reaction rate. The key to improve the performance of electrochemical sensor is to modify the electrode sensitive material on the surface of the sensor electrode to realize electrochemical signal amplification. Biochar material is an excellent electrode modification material because of its rich pore structure, large specific surface area, excellent adsorption capacity, and the oxygen-containing active functional groups on its surface. However, due to the variety of synthesis methods of biochar materials and the complexity of its composition, the detection limit of biochar-based electrochemical sensors still need to be improved, and the sensing mechanism of biochar-based electrochemical sensors is still unclear. This review summarizes the research progress of biochar based electrochemical sensors in the detection of environmental pollutants, drugs and biomolecular on the basis of briefly describing the synthesis methods and the structural properties of biochar based materials. At present, the analysis of environmental pollutants mainly focuses on phenols and quinones, and is gradually expanding to new pollutants such as microplastics. The target substances for drug testing are mainly antibiotics and flavonoids in traditional Chinese medicine, with relatively less research on the detection of other substances. In biological molecule detection, glucose, dopamine, uric acid, and ascorbic acid are widely monitored, and the detection mechanism is also relatively clear. Overall, there is still significant demand for improving the detection limit and sensitivity of the constructed sensors, and the sensors based on large electrochemical workstations are gradually transitioning towards centralized, miniaturized, and portable sensing platforms. Finally, the development direction of electrochemical sensing analysis technology based on biochar materials is proposed: (1) It is necessary to optimize the structure of carbon materials, regulate the composition of carbon materials, prepare high-performance biochar-based materials that are more suitable for electrochemical sensors, so as to reduce the detection limit and improve the sensitivity; (2) It is urgent to fabricate portable sensors based on biochar to realize rapid and intelligent analysis and detection; (3) The sensing mechanism and the testing performance improvement mechanism are the problems that must be deeply explored.