The disclosure is a network interface controller (NIC) capable of sharing buffers, which is coupled to a host and a network to make the network connection. The NIC includes a transmitting buffer, a transmitting controller, a receiving buffer, and a receiving controller. The transmitting controller controls the transmitting buffer to transmit the transmission data provided by the host to the network. The receiving controller controls the receiving buffer to transmit the reception data received from the network to the host, and determines a storage capacity of the receiving buffer. When the storage capacity is smaller than a set value, the receiving controller transmits a request signal to the transmitting controller, the transmitting controller generates a response signal according to the request signal and a status signal corresponding to the transmitting buffer, and the receiving controller controls whether reception data is stored in the transmitting buffer according to the response signal.