A data access method, wherein the method is applied to a host, the host comprises a processor, a memory, and a physical interface card, a virtual machine that runs on the host, wherein the virtual machine comprises a virtual machine interface card; and the method comprises: obtaining, by the processor, a first descriptor from the memory, wherein the first descriptor comprises a virtual machine physical memory address and a data length of accessible data, the accessible data is accessible by the physical interface card, the virtual machine physical memory address points to a start location at which the accessible data is stored in a physical memory of the virtual machine, and the first descriptor is encoded in a coding mode that can be recognized by the virtual machine interface card; characterised in that: the first descriptor is encoded in a coding mode that cannot be recognized by the physical interface card; converting, by the processor, the first descriptor to a second descriptor, wherein the second descriptor is encoded in a coding mode that can be recognized by the physical interface card, the second descriptor comprises a virtual machine physical memory address and the data length; and obtaining, by the physical interface card based on the second descriptor, a physical address (1, 2) that is in the memory and to which the virtual machine physical memory address is mapped, and accessing the accessible data according to the physical address in the memory and the data length. the virtual machine comprises a virtual machine interface card; and the method comprises: obtaining, by the processor, a first descriptor from the memory, wherein the first descriptor comprises a virtual machine physical memory address and a data length of accessible data, the accessible data is accessible by the physical interface card, the virtual machine physical memory address points to a start location at which the accessible data is stored in a physical memory of the virtual machine, and the first descriptor is encoded in a coding mode that can be recognized by the virtual machine interface card; characterised in that: the first descriptor is encoded in a coding mode that cannot be recognized by the physical interface card; converting, by the processor, the first descriptor to a second descriptor, wherein the second descriptor is encoded in a coding mode that can be recognized by the physical interface card, the second descriptor comprises a virtual machine physical memory address and the data length; and obtaining, by the physical interface card based on the second descriptor, a physical address (1, 2) that is in the memory and to which the virtual machine physical memory address is mapped, and accessing the accessible data according to the physical address in the memory and the data length. obtaining, by the processor, a first descriptor from the memory, wherein the first descriptor comprises a virtual machine physical memory address and a data length of accessible data, the accessible data is accessible by the physical interface card, the virtual machine physical memory address points to a start location at which the accessible data is stored in a physical memory of the virtual machine, and the first descriptor is encoded in a coding mode that can be recognized by the virtual machine interface card; characterised in that: the first descriptor is encoded in a coding mode that cannot be recognized by the physical interface card; converting, by the processor, the first descriptor to a second descriptor, wherein the second descriptor is encoded in a coding mode that can be recognized by the physical interface card, the second descriptor comprises a virtual machine physical memory address and the data length; and obtaining, by the physical interface card based on the second descriptor, a physical address (1, 2) that is in the memory and to which the virtual machine physical memory address is mapped, and accessing the accessible data according to the physical address in the memory and the data length. the first descriptor is encoded in a coding mode that cannot be recognized by the physical interface card; converting, by the processor, the first descriptor to a second descriptor, wherein the second descriptor is encoded in a coding mode that can be recognized by the physical interface card, the second descriptor comprises a virtual machine physical memory address and the data length; and obtaining, by the physical interface card based on the second descriptor, a physical address (1, 2) that is in the memory and to which the virtual machine physical memory address is mapped, and accessing the accessible data according to the physical address in the memory and the data length.