Improving the specific capture efficiency of CTCs, and meanwhile preventing the nonspecific adsorption of surrounding background cells, is the main focus of CTCs detection. Herein, a novel biomimetic microfluidic system was developed by combining the unique benefits of biomimetic nanoparticles and microfluidic techniques. The magnetic nanoclusters were camouflaged with leukocyte membrane fragments and decorated with aptamer SYL3C specific for EpCAM positive tumor cells and then loaded into the microfluidic chip with the help of magnets. By use of this system, more than 90% of the rare tumor cells in blood could be captured and detected within 20 min with almost no leukocyte background, indicating a great practical application potential for CTCs detection.