The interaction of low dielectric constant amorphous fluoropolymer (AF) film with evaporation-deposited aluminum has been investigated via high-resolution X-ray photoelectron spectroscopy (XPS). For the sake of gaining the interface of the AV AF sample, the partial aluminum has been removed by Ar ion etching. In situ XPS measurements show that Al fluoride, C-O-Al and Al carbide are formed at the interface between aluminum and AE The formation of Al fluoride results mainly from a reaction between Al atom and F free radicals due to the breakage of one C-F bond in CF3 groups, meanwhile, this also leads to an increase in CF2 groups. After annealing, the relative content of C-F bonds at the interface decreases remarkably, and the relative concentrations of C-O-Al and Al-C complexes increase evidently. However, the relative percentage of Al fluoride decreases, indicating that Al fluoride has higher fluidity than the C-O-Al and AI-C complexes against annealing. Moreover, the relative percentages of the elements at the interface show that the annealing causes a little diffusion of Al into the AF film. Possible reaction mechanisms of Al with AF are also discussed.