Provided are a transmission method, apparatus and system. The transmission method includes: in response to UCI being configured to be transmitted in a PUSCH, and the PUSCH does not have a UL-SCH, determining to transmit the UCI according to an actual code rate of the UCI and a preset threshold. The preset threshold is determined according to a predetermined code rate and a predetermined value β. In the embodiment of the present disclosure, when the UCI is transmitted based on a given modulation mode, the UCI is determined to be transmitted according to the actual code rate of the UCI and the preset threshold.