In this research, the extraction, isolation and purification of the polysaccharides from Caulis Lonicerae were performed, and their functions to removing nitrite and block the synthesis of nitrosamine were determined. The ultrasound-assisted polysaccharide extraction was optimized using the yield of polysaccharides from Caulis Lonicerae as the index, and the response surface method. The extracted polysaccharides was deproteinized using the Sevag method, precipitated using alcohol, and vacuum dried, before the examinations on their abilities of scavenging nitrite and blocking nitrosamine synthesis under simulated gastric acid conditions. The results indicated the optimal extraction conditions: the ratio of liquid to material, 30:1; extraction time, 40 min; ultrasonic power, 210 W; extraction temperature, 70 ℃. Under the optimal conditions, the theoretical yield of polysaccharides was 8.53%, while the experimental value was 8.46%; at a concentration of 500 μg/mL, the polysaccharide extract had a nitrite-scavenging rate of 90.44% and a blocking rate of 71.24% for nitrosamine synthesis. Therefore, the response surface method, which was used to optimize the ultrasound-assisted extraction of polysaccharides from Caulis Lonicerae, provided good quality predictions. The obtained polysaccharides were capable of removing nitrite and blocking the synthesis of nitrosamines. This research provides a theoretical basis for further utilization of Caulis Lonicerae and development of derived bioactive polysaccharide products.