A method for transmitting a signal in a device-to-device proximity service, comprising: allocating, by a base station, at least one time-frequency resource set to each user cluster in N user clusters in a cell covered by the base station, wherein at least two time-frequency resource sets in M time-frequency resource sets allocated by the base station to the N user clusters are different from each other, wherein N is an integer not less than 2, and M is an integer not less than N, wherein the M time-frequency resource sets are all physical resource block time-frequency resource sets; and transmitting, by the base station, R th information to the R th user cluster in the N user clusters, wherein the R th information is used to indicate an R th time-frequency resource set that is allocated by the base station to the R th user cluster, wherein a value of R is 1, 2,..., N separately; wherein the allocating, by the base station, the at least one time-frequency resource set to each user cluster in the N user clusters is performed such that any two time-frequency resource sets in the M time-frequency resource sets have no intersection set; or the allocating, by the base station, the at least one time-frequency resource set to each user cluster in the N user clusters is performed according to information about interference between the N user clusters; and the method further comprises the steps of: receiving, by the base station, a first message that is sent by the first user equipment in the R th user cluster and that carries a resource level of P, wherein the first message is used to indicate that the first user equipment uses the (1+P×k) th to the (P×(k+1)) th physical resource blocks of the R th time-frequency resource set to send a signal to a second user equipment in the R th user cluster, wherein P is a positive integer not greater than Q, a value range of k is a non-negative integer less than a rounded number of (Q/P), and Q is a quantity of physical resource blocks comprised in the R th time-frequency resource set; and sending, by the base station according to the first message, a second message that carries the resource level of P to the second user equipment, so that the second user equipment uses the second message when detecting, on the R th time-frequency resource set, the signal sent by the first user equipment. allocating, by a base station, at least one time-frequency resource set to each user cluster in N user clusters in a cell covered by the base station, wherein at least two time-frequency resource sets in M time-frequency resource sets allocated by the base station to the N user clusters are different from each other, wherein N is an integer not less than 2, and M is an integer not less than N, wherein the M time-frequency resource sets are all physical resource block time-frequency resource sets; and transmitting, by the base station, R th information to the R th user cluster in the N user clusters, wherein the R th information is used to indicate an R th time-frequency resource set that is allocated by the base station to the R th user cluster, wherein a value of R is 1, 2,..., N separately; wherein the allocating, by the base station, the at least one time-frequency resource set to each user cluster in the N user clusters is performed such that any two time-frequency resource sets in the M time-frequency resource sets have no intersection set; or the allocating, by the base station, the at least one time-frequency resource set to each user cluster in the N user clusters is performed according to information about interference between the N user clusters; and the method further comprises the steps of: receiving, by the base station, a first message that is sent by the first user equipment in the R th user cluster and that carries a resource level of P, wherein the first message is used to indicate that the first user equipment uses the (1+P×k) th to the (P×(k+1)) th physical resource blocks of the R th time-frequency resource set to send a signal to a second user equipment in the R th user cluster, wherein P is a positive integer not greater than Q, a value range of k is a non-negative integer less than a rounded number of (Q/P), and Q is a quantity of physical resource blocks comprised in the R th time-frequency resource set; and sending, by the base station according to the first message, a second message that carries the resource level of P to the second user equipment, so that the second user equipment uses the second message when detecting, on the R th time-frequency resource set, the signal sent by the first user equipment. receiving, by the base station, a first message that is sent by the first user equipment in the R th user cluster and that carries a resource level of P, wherein the first message is used to indicate that the first user equipment uses the (1+P×k) th to the (P×(k+1)) th physical resource blocks of the R th time-frequency resource set to send a signal to a second user equipment in the R th user cluster, wherein P is a positive integer not greater than Q, a value range of k is a non-negative integer less than a rounded number of (Q/P), and Q is a quantity of physical resource blocks comprised in the R th time-frequency resource set; and sending, by the base station according to the first message, a second message that carries the resource level of P to the second user equipment, so that the second user equipment uses the second message when detecting, on the R th time-frequency resource set, the signal sent by the first user equipment.