Abstract: A downlink transmission method in a Coordinated Multi-Point (COMP) transmission system, a network device, and a wireless system are disclosed. The method includes: determining a downlink physical resource and a downlink mapping rule corresponding to a physical downlink channel and/or a reference signal negotiated by cooperating cells; and mapping the physical downlink channel and/or the reference signal to the downlink physical resource according to the downlink mapping rule, and sending the physical downlink channel and/or the reference signal to a User Equipment (UE). According to the method, effective coverage can be improved and the problem of mutual interference between cells can be prevented.