Embodiments of the invention disclose a data transmission method, a device, and a computer storage medium to perform data transmission. A congestion status of a transmission port is obtained by a first device. The transmission port is a communications port used by the first device when a second device transmits data to the first device. The congestion status is used to indicate whether data congestion occurs on the transmission port. Indication information is sent to the second device when a mode switching condition is met. The indication information is used to instruct the second device to switch a transmission mode used when the second device transmits the data, so that the second device transmits the data to the first device in a switched transmission mode, and the mode switching condition is associated with the congestion status of the transmission port.