A transmission control method includes sending or receiving, by a first device, first data to or from a second device through a first communication connection, detecting, by the first device when sending or receiving the first data to or from the second device through the first communication connection, that an error has occurred on the first communication connection, and sending, by the first device, error information of the first communication connection to the second device through a second communication connection, where the second communication connection is different from the first communication connection, and the error information indicates that the error has occurred on the first communication connection.