A memory access method, comprising: sending, by a memory controller, a memory access instruction, a lower-order address signal, a first chip select signal, and a first higher-order address signal to a first level buffer chip, performing delay processing on a second higher-order address signal to obtain a delayed address signal, and sending the delayed address signal to a second level buffer chip, wherein: the first level buffer chip is cascaded with the second level buffer chip; the second level buffer chip is connected to at least one memory module, wherein the memory module comprises at least one memory chip; the first chip select signal and the first higher-order address signal are used to identify a target second level buffer chip from the second level buffer chips; and the lower-order address signal is used to identify a target memory chip in a target memory module; outputting, by the first level buffer chip, a second chip select signal to the second level buffer chip according to a preset mapping relationship, the first chip select signal, and the first higher-order address signal to gate the target second level buffer chip, and sending the memory access instruction and the lower-order address signal to the target second level buffer chip, wherein the second level buffer chip comprises at least one buffer chip, and the target second level buffer chip is a buffer chip that is gated by using the second chip select signal and is from the second level buffer chips; determining, by the target second level buffer chip, the target memory module from the at least one memory module according to the delayed address signal and the second chip select signal, and determining the target memory chip from the target memory module according to the lower-order address signal, wherein the delayed address signal and the second chip select signal are used to identify the target memory module in the at least one memory module; and acquiring, by the target second level buffer chip, target data from the target memory chip according to the memory access instruction, and sending the target data to the memory controller by using the first level buffer chip. sending, by a memory controller, a memory access instruction, a lower-order address signal, a first chip select signal, and a first higher-order address signal to a first level buffer chip, performing delay processing on a second higher-order address signal to obtain a delayed address signal, and sending the delayed address signal to a second level buffer chip, wherein: the first level buffer chip is cascaded with the second level buffer chip; the second level buffer chip is connected to at least one memory module, wherein the memory module comprises at least one memory chip; the first chip select signal and the first higher-order address signal are used to identify a target second level buffer chip from the second level buffer chips; and the lower-order address signal is used to identify a target memory chip in a target memory module; outputting, by the first level buffer chip, a second chip select signal to the second level buffer chip according to a preset mapping relationship, the first chip select signal, and the first higher-order address signal to gate the target second level buffer chip, and sending the memory access instruction and the lower-order address signal to the target second level buffer chip, wherein the second level buffer chip comprises at least one buffer chip, and the target second level buffer chip is a buffer chip that is gated by using the second chip select signal and is from the second level buffer chips; determining, by the target second level buffer chip, the target memory module from the at least one memory module according to the delayed address signal and the second chip select signal, and determining the target memory chip from the target memory module according to the lower-order address signal, wherein the delayed address signal and the second chip select signal are used to identify the target memory module in the at least one memory module; and acquiring, by the target second level buffer chip, target data from the target memory chip according to the memory access instruction, and sending the target data to the memory controller by using the first level buffer chip.