The invention discloses diphenoxyl flexible molecules with high affinity with A[beta] plaque and a preparation method and applications thereof. After the molecules are labeled by radionuclide, the molecules can be used as an A[beta] plaque developing agent to diagnose Alzheimer's disease; and the structure of the molecules is represented in the description. The chemical structure of the molecules is different from the structures of disclosed compounds, and the molecules are novel molecules for diagnosing Alzheimer's disease. After the molecules are labeled by radionuclide, the obtained A[beta] plaque developing agent has the advantages of good in-vitro stability, low lipid solubility, quick brain removing speed, wide application prospect and great market value.