A peripheral component interconnect express (PCIe) interface system is provided to include a PCIe interface device, a host, and a non-volatile memory express (NVMe) device connected to the host through the interface device. The host includes a host memory configured to store information on a command to be executed on the NVMe device and a command that has been executed on the NVMe device, and an NVMe driver configured to transmit the command to be executed on the NVMe device to the host memory, and output a doorbell signal indicating that the command to be executed on the NVMe device has been stored in the host memory to the NVMe device. The NVMe device requests to the host memory to register a lightweight notification (LN) indicating a position in which the command to be executed on the NVMe device is stored.