The present disclosure provides a method and an apparatus for transmitting an uplink control signal. The method includes: transmitting M predefined sequences on two transmission symbols within a transmission time interval, and determining an acknowledgement (ACK) message or a negative acknowledgement (NACK) message according to the M predefined sequences and mapping patterns of the M predefined sequences in a time domain and a frequency domain, where M is a positive integer. By means of the above technical solution, a problem that a transmission structure for transmitting the ACK message and the NACK message is imperfect when the transmission time interval is equal to the length of two symbols is solved, and the transmitting of the ACK message and the NACK message when the transmission time interval is equal to the length of two symbols is perfected.