The invention relates to a benzopyran-4-one substituted naphthalimide-polyamine conjugate and a preparing method and usage thereof. The naphthalimide-polyamine conjugate has a structure as shown in a formula I. The benzopyran-4-one substituted naphthalimide-polyamine conjugate has obvious inhibition activity for cell proliferation of multiple tumor cells such as HCT-116 (human colon cancer cell), HepG2 (human hepatoma carcinoma cell), K562 (human chronic myeloid leukemia cells) and SMMC7721 (human hepatoma carcinoma cell); the conjugate can also serve as a targeting mitochondria fluorescence probe and can effectively inhibit pulmonary metastasis of the tumor, wherein a is 0, 1 or 2, m is 1, 2 or 3, n is 1, 2, 3, or 4, R is H or CH3, and R1 is shown in the description.