In order to solve the problem of poor resource allocation effect of 5G communication network, the research on resource allocation method of 5G communication network based on intelligent optimization is put forward. In this paper, under the resource allocation of 5G network slices, a traffic prediction model of 5G communication network based on Prophet-PFMGNet is formed to predict the traffic and resource demand of 5G communication network, and the cuckoo is used to optimize the resource allocation result and obtain the best resource allocation of 5G communication network. The experimental results show that this method has a good network traffic prediction effect, and the deterministic correlation coefficients are all above 0.92, which can reliably predict the resource demand. After application, the utilization rates of network nodes and links are all above 0.93, and the blocking probability of users is all below 0.06.