A Peripheral Component Interconnect Express (PCIe) data transmission method includes a first node that obtains a transaction layer packet (TLP). The TLP includes a TLP header, a TLP extension header, and data. The TLP header includes a type field, an Fmt field, and a reserved bit, and where the type field, the Fmt field, the reserved bit, and the TLP extension header indicate a data type of the data and at least one piece of attribute information corresponding to the data type such that, information, the data type and the at least one piece of the attribute information, to transmit the data is indicated using the type field, the Fmt field, the reserved bit, and the TLP extension header in the TLP.