A method based on strand displacement amplification (SDA) and electrochemical aptamer sensor technology was constructed to detect ochratoxin A (OTA) in food. According to the OTA specific aptamers， the hairpin structure was designed， and the SDA reaction recognition sites were set in the stems of the hairpin structure. SDA amplification was carried out. The amplified products were hybridized with the electrochemical probe modified ferrocene (FC) to change the electrical signal， so as to establish an electrochemical aptamer sensor for detecting OTA. The specificity of the method was evaluated through the determination of seven groups of different toxins， and its sensitivity and detection limit were determined. The results were compared with the national standard of ochratoxin A enzyme linked immunosorbent assay (ELISA) (GB 5009.96-2016). The results showed that under the optimal conditions， the linear range of the sensitivity of the electrochemical aptamer sensor was 0.1 pg/mL - 10 ng/mL， the detection limit (LOD) was 0.05 pg/mL. When OTA exists， the test result is positive， and when OTA does not exist， the test result is negative， indicating that the specificity of this method is good. In the manual spiked test， the spiked recovery of the electrochemical aptamer sensor is 96.60%-99.04% and that of ELISA (national standard) is 94.00%-98.50%. Therefore， the spiked recovery of this method is better than that of the national standard method. In conclusion， this method has the potential of rapid detection of OTA in food， provides a new detection idea for rapid detection of OTA in food， and has high practical value.