Food safety has been the focus problem concerned by the society and the general public whose current state is serious, so it is of great practical significance to realize the rapid detection of harmful substances in food. Synthetic pigment is a common food additive whose excessive and illegal addition is still one of the important problems in food safety, which greatly endangers the health of the people and the healthy development of food industry. Common synthetic pigment detection methods have the disadvantages of long time consumption and high cost, which are not suitable for real-time monitoring and rapid screening of synthetic pigments. In order to overcome the shortcomings of the traditional methods, this paper proposes the use of surface-enhanced Raman spectroscopy to detect synthetic pigments. This method has the advantages of fast detection speed and high detection sensitivity, and can achieve real-time detection in the field. In addition, since Raman detection methods often rely on complex sample preparation operations, and common solid phase extraction techniques rely on manual operations, which are complicated and time consuming, and seriously restrict the rapid detection efficiency of food. Therefore, in this paper, the automatic solid phase extraction device, including mechanical, electrical and software modules, was designed, and by precise control of peristaltic pump flow rate and multi-way valve switch in four steps of activation, loading, rinsing and elution, the device realized the automatic fast solid phase extraction of food samples. In the experimental part, the juice drink with different patent blue V concentrations was prepared, and then the device was used to pre-treat the patent blue V in the juice, in which the extraction column packing and the time and parameters of each step were rationally selected, and then the Raman spectra of patented blue V were successfully detected. The experimental results showed that, compared with traditional manual extraction, the automatic solid phase extraction device has saved nearly half of the extraction time (10 minutes down to 5 minutes) and can process five samples at the same time. The extraction time was not easy to be affected by human factors which significantly improved the efficiency and stability of the sample pretreatment. Meanwhile, because it was relatively less interfered by the external environment, a stronger Raman spectral signal (about 50% enhancement) could be obtained, so the extraction effect was also satisfactory. The results of different concentrations of patented blue V samples show that the method can achieve a detection concentration of 0.5 mg·L-1, which can effectively meet the needs of on-site monitoring, and is characterized by fast, convenient and high sensitivity.