The present invention provides a data read/write system. The data read/write system includes a memory controller and a memory module. The memory controller includes a first control circuit, a data output circuit, and a data receiving circuit. The memory module includes a memory buffer and at least two memory chips. The memory buffer includes a second control circuit, a write circuit, and a read circuit. The advantage of the present invention is that, when data is read or written into the memory chip, especially a DDR4 X4 memory chip, low power consumption of interface data transmission can be achieved through a data bus inversion control line DBI.