It is provided a method, device and system for transmitting an ACK response in bidirectional data transmission. When receiving windows on both sides of a transmission are simultaneously full, no new information frames can be transmitted to the other side before the ACK timer times out. This situation is called an ACK interlock delay. In the present disclosure, a communication device actively transmits a control frame carrying an ACK response to an opposite communication terminal when it detects that the local receiving window and the receiving window of the opposite communication terminal are both full, thus avoiding ACK interlock delays, avoiding wasting time, and improving the rate of transmission and link establishment.