In this work, sulfhydryl functionalized carbon dots (SH-CDs) were synthesized for the first time by a two-step hydrothermal method. The sulfhydryl group in SH-CDs can be converted efficiently and reversibly in a few minutes under redox conditions. On this basis, ochratoxin A (OTA) induced hybrid chain reaction amplification and alk. phosphatase enzymic hydrolysis to produce ascorbic acid (AA). AA reduced the aggregated SH-CDs, thereby realizing the dual-mode rapid quant. anal. of the OTA concentration by measuring the changes in the fluorescence intensity and absorbance of the SH-CDs solution The proposed sensor has a good linear relationship with the OTA concentration in the range of 2.0-5.0 nM, and the lowest detection limit is 2.0 nM. Addnl., the visual color change of the solution can improve the simplicity and accuracy of semi-quant. detection of OTA with the naked eye. In short, this method has the advantages of rapidity, sensitivity, reversibility and visualization.