Aiming at the demand for rapid detection of food residues on the surface of equipment during food processing, a portable fluorescence imaging detection system was developed using spinach juice as an example, and on this basis, the quantitative function of the system for chlorophyll A, which is a substance with high content in spinach juice, was added. The system is mainly composed of a light source, a CCD camera, a display and a control and processing unit, and the light source and filter used to stimulate the substance to produce fluorescence can be adjusted and replaced according to the actual demand, while the control software of the detection system is developed, and the display is used for human-machine interactive operation, mainly realizing the functions of image data acquisition and processing. Qualitative experiments were carried out on spinach juice residues on the surface of three widely used food processing materials, and the detection results showed that the portable fluorescence imaging detection system was able to better identify chlorophyll residues on the food processing surface when the surface itself did not have a fluorescence effect. The quantitative detection results of chlorophyll A showed that when the concentration of chlorophyll A solution was in the range of 0-8.5 μg/mL, the determination coefficient R2 of the concentration prediction model can reach 0.99, and the root mean square error (RMSE) of the prediction results was not higher than 0.24 μg/mL. The results of this study show that the developed portable fluorescence imaging detection system is feasible and effective for the detection of substances with specific fluorescence effects, and the system has the advantages of a large field of view, small size and easy to carry, etc. The system can be used for real-time on-site detection, and in addition to the detection of food residues on the surface of food processing, it can also be extended to the detection of plant pathology and other fields, which has a broader application prospect.