In a system and method of control channel transmission in the communications field, REs, except those used for transmitting a DMRS, are grouped in each physical resource block pair of L physical resource block pairs. The L physical resource block pairs are determined to be used to transmit a control channel into N eREGs. The number of valid REs are calculated except other overheads in each eREG of the N eREGs. Each of the eCCEs are mapped onto M eREGs according to the number of valid REs included in each eREG of the N eREGs of each physical resource block pair. The eCCE is sent in the REs included in the eREG.