The invention discloses a submission method of a descriptor of an NIC based on mixing of PIO and DMA. The implementation steps are as follows: 1) a hardware transmit queue is built in an NIC, and a main store transmit queue is built in a main store; 2) a descriptor is initialized; and 3) a consumer process accesses the NIC directly to write the descriptor into the hardware transmit queue directly in a PIO manner, or the descriptor is submitted to the main transmit queue, while door-bell data is written into the hardware transmit queue; when the NIC processes the data of the hardware transmit queue sequentially, current data type is judged, if the current data is the descriptor, and read-back processing is performed from the hardware transmit queue according to the value of a length field; and if the current data is the door-bell data, the current data is retaken and then processed from the main store transmit queue, and a process that the NIC implements the DMA to read a next descriptor and a process of processing the current descriptor are overlapped. The submission method has the advantages that the message start delay is small, the capacity of the transmit queue is large, and data are processed simply and efficiently.