In this work, dispersed magnetic covalent organic framework nanospheres (MCOF) with uniformed Fe₃O₄ nano-assembly as cores and high-crystalline COF as shells were prepared by monomer-mediated in-situ interface growth strategy. Based on the unique interaction between MCOF and hairpin DNA, a fluorescent signal amplified miRNA biosensor was constructed. It could realize the sensitive detection of miRNA-182 in different matrixes, which possessed the low detection limit, wide linearity range, good stability and precision and high extraction recovery. These findings suggest a robust way for sensitive detection and accurate diagnosis/prognosis of glioma. This work was mainly accomplished by Ph.D. candidate Dong Liang and Master candidate Xiaoyi Zhang.