Objectives: A rapid separation and enrichment technology for foodborne pathogens has been developed， providing a new method for rapid detection of foodborne diseases and a new approach for online food safety monitoring. Methods: A microfluidic chip system based on electromagnetically driven magnetic bead chains was proposed for the first time to achieve online magnetic separation of bacteria in continuous flow. The system utilizes a high-gradient magnetic field generated by an electromagnetic actuation device to form high-density magnetic bead chains from aptamer-conjugated magnetic beads， which occupy the cross-section of the separation channel. Target bacteria are specifically captured and separated by the magnetic bead chains upon flowing into the separation channel. Results: Under optimized experimental conditions， the system was able to detect Salmonella typhimurium at concentrations as low as 12 CFU/mL within 20 minutes. In pure bacterial suspensions， the capture efficiency for the target bacteria ranged from 55.4% to 80%； even in the complex matrix of milk， the capture efficiency remained between 46.2% and 69.7%. Furthermore， experiments confirmed that the capture efficiency of the system for the target bacteria and their mixed populations was significantly higher than that for non-target bacteria， demonstrating its excellent specificity. Conclusions: The magnetic bead chain-based microfluidic chip system developed in this study provides a novel approach for the rapid online detection of foodborne pathogens. This system not only achieves fast and specific bacterial separation at the methodological level but also offers technical support for enhancing the efficiency of online food safety monitoring.