Abstract: Food is the paramount necessity of the people, safety is the first concern for the food, under the background of widespread application of various pesticides and food additives, illegal food additives have a serious impact on the food safety situation, and the qualitative detection of trace amounts of illegal food additives is of great significance. In order to achieve qualitative detection of pyridine, a sensing system based on HCPCF (Hollow Core Photonic Crystal Fiber) SERS was proposed. Silver nanoparticles were used to make SERS substrate, and SERS signal devices were designed to collect SERS in the same direction. By means of cone pulling on HCPCF to achieve selective filling, the detection scheme of collecting output signals by spectrometer was implemented. After the liquid pyridine sample with the concentration of 0.004 975% was detected, the obvious SERS characteristic spectrum could be observed. The experimental results show that the sensing system can achieve qualitative trace detection of pyridine in the liquid sample.