The invention provides a method for preparing porous Fe-based amorphous alloy-Al-based composite materials, comprising the following steps: (1) mixing Fe-based amorphous alloy powder, Si powder, and diamond powder in a certain proportion, then adding a composite binder and mixing uniformly to obtain a mixture; (2) pressing the mixture into a regular-shaped porous preform; (3) placing the porous preform in an oven for drying treatment to obtain a dehydrated preform; (4) placing the dehydrated preform into a tube furnace for the first stage of high-temperature treatment, and obtaining a degreased mixture framework after cooling; (5) placing the degreased mixture framework and aluminum into a tube furnace for the second stage of high-temperature treatment, and obtaining the porous Fe-based amorphous alloy-Al-based composite material after cooling. The invention indirectly regulates the density of the porous Fe-based amorphous alloy-Al-based composite material by changing the initial diamond powder content, thereby preparing a porous Fe-based amorphous alloy-Al-based composite material with excellent performance.