A method of transmitting downlink control information, a terminal, and a network side device are provided. The method comprises: determining, by a terminal, resource configuration information corresponding to a control resource set; acquiring, by the terminal, blind detection information based on a first correspondence relation between the resource configuration information and the blind detection information, wherein the blind detection information includes at least one of: a length of the downlink control information DCI, an aggregation level of candidate control channels, and a length of a resource allocation RA field in the DCI; and receiving, by the terminal based on the blind detection information, DCI transmitted by the network side device on the control resource set.