A downlink control channel transmission method, a terminal and a network side device are provided. The method includes: selecting, in a case that monitoring occasions of search spaces transmitted in different Control Resource Sets (CORESETs) configured with different beam directions collide, a target CORESET from the different CORESETs according to types of the search spaces where the collision occurs, wherein the collision during the monitoring occasions comprises that the monitoring occasions are the same and configured resources of the different CORESETs overlap, or, that a time interval between the monitoring occasions is less than a specified threshold; and detecting and receiving a downlink control channel according to a beam direction of the target CORESET.