The present invention provides a method for sending and receiving control information, an apparatus and a communication system. The method for sending control information includes: setting respective control bits in a downlink control information (DCI) format to generate control information applied by a network side to a terminal, wherein indication information indicating whether to swap a corresponding relationship between a transmission block and a codeword is not carried in a control bit in the DCI format, if a dedicated demodulation reference signal used to demodulate data is preconfigured by the network side for the terminal and respective codewords correspond to the same number of layers; and the indication information is carried in a control bit in the DCI format, if the dedicated demodulation reference signal used to demodulate data is not preconfigured by the network side for the terminal; and sending the generated control information to the terminal.