Provided are a preamble transmission method and apparatus. The method comprises: a UE executing LBT on a first time frequency resource of an unlicensed carrier until a right to use the unlicensed carrier is acquired, wherein the LBT comprises LBT executed for transmitting a preamble; and after a right to use the access to the unlicensed carrier is acquired, the UE transmitting the preamble on a second time frequency resource located behind the first time frequency resource, wherein the second time frequency resource is a pre-configured PRACH time frequency resource at a fixed position, or a PRACH time frequency resource determined according to an LBT execution position. By means of the present disclosure, the problem in the relevant art of intra-cell interference caused by uplink data transmission over an unlicensed carrier is solved, and the uplink data transmission quality is improved.