Packet sending control method, and processing method, device and system

Embodiments of the present invention provide a packet sending control method, and a processing method, device and system. The method comprises: a packet sending control device obtaining available space information of a receiving channel corresponding to each packet of a first protocol type in a receiving end device, and sending an indication packet of a second protocol type carrying the available space information to a packet sending processing device, so that the packet sending processing device performs, according to the available space information, sending control on the packet of the first protocol type sent from a sending end device. With the packet sending control method provided by the embodiment of the present invention, the packet sending processing device performs, according to the available space information, sending control on the packet sent from the sending end device, and sends the packet only when the available space information of the packet is valid, thereby effectively avoiding a deadlock problem caused by non-matching virtual channels during conversion of packets between different protocols.