Abstract: The embodiments of the invention disclose a data transmission method comprising: a base station receives terminal information transmitted by terminal equipment; the base station determines, according to the terminal information, that the terminal equipment is able to communicate with the base station via a first relay node; and the base station transmits to the terminal equipment a first notification message to, instruct the terminal equipment to communicate with the base station via the first relay node. In the embodiment of the invention, the base station can instruct the terminal equipment to switch from a cellular link to a sidelink passing through the first relay node, thereby ensuring communication quality between the terminal equipment and the base station.