This application discloses a floating-point number multiplication computation method, an apparatus, and an arithmetic logic unit. The method includes: obtaining a plurality of to-be-computed first-precision floating-point numbers; decomposing each to-be-computed first-precision floating-point number to obtain at least two second-precision floating-point numbers, a second precision of the second-precision floating-point number is lower than a first precision of the first-precision floating-point number; determining various combinations including two second-precision floating-point numbers obtained by decomposing different first-precision floating-point numbers; inputting the second-precision floating-point numbers in each combination into a second-precision multiplier to obtain an intermediate computation result corresponding to each combination; and determining a computation result for the plurality of to-be-computed first-precision floating-point numbers based on the intermediate computation result corresponding to each combination.