Abstract: The immuno magnetic nanobeads were a rapid method which can be used to isolate the target bacteria directly from food samples to ensure follow-up detection.Combining with the reliable conventional surface plating methods and the superparamagnetic nanobeads, the influence of the antibody quantity added and the dose of immuno magnetic nanobeads was determined by the capturing efficiency.Meanwhile, the immuno magnetic nanobeads was used to capture the shigella flexneri in pure broths and lamb wash water at concentration of 100¹03CFU/mL.The results showed that the optimal amount of the shigella polyclonal antibody (4⁵mg/mL) for conjugation of 1mL streptavidin nanobeads ( (180±20) nm, 2mg/mL) was 70μL, and the optimized amount of immuno magnetic nanobeads used for capture of target bacteria at concentration of 102¹04CFU/mL was 60μL.For pure broths and lamb wash water, the capture limit could reach to 100CFU/mL and 101CFU/mL within 1h, respectively.This study optimized the test conditions and provided a theoretical basis for immuno magnetic beads rapid enrichment of target bacteria.