The invention discloses a user access method for ensuring low delay transmission of content in a future 5G network, and belongs to the field of mobile communication. The method comprises the steps of firstly constructing a small base station mobile network simulation scene with a cache, dividing users into several relatively large clusters according to the required content, and counting the sum of upper limits of multicasting groups of all base stations, and the sum of upper limits of the number of acceptable users, and deleting residual clusters according to the limitation, continuously judging, if the number of the user clusters are less than the sum of the upper limits of the multicasting groups, screening and classifying each cluster, further dividing the cluster into sub-clusters to allow the number of the user clusters to be equal to the sum of the upper limits of the multicasting groups; then executing a KM algorithm on multicasting frequency bands of all sub-clusters and the base station; and at last, sending a user clustering result and a base station accessing result to the user by the base station, thus completing communication. According to the method provided by the invention, limited channel resources are used for serving more users, service efficiency of the base station is improved, unnecessary wireless link transmission is reduced, overall delay of a content distribution process is reduced, and thus the overall delay of the users in the system is minimized.