Provided are a channel detection method and device and an information transmission method and device. The channel detection method comprises: a transmission device determining a CWS for channel detection according to first information, wherein the first information comprises feedback information corresponding to a reference physical channel and transmitted by the transmission device on an unlicensed carrier, and the feedback information comprises at least one of TB-HARQ information and CBG-HARQ information; and the transmission device performing channel detection on the unlicensed carrier according to the CWS.