In a cache-enabled cellular network, a large number of repeated requests by users for hotspot contents in the network will increase the traffic load and the content delivery delay. Therefore, edge caching technology is introduced to cache highly popular content files in advance in cache devices closer to users to reduce the content delivery delay. However, the improvement of system performance by mobile edge caching technology will be limited by the storage capacity of the base station (BS). This paper studied the content delivery algorithm in cellular networks with BS cooperative caching capability which takes minimizing the system cost as the optimization goal. The content delivery strategy of the accessing BS and the content delivery strategy of the cooperative BS are constructed as two 0-1 matrix variables, which are used to indicate what contents the BSs deliver to the users at a certain moment. the coupling variables are solved by Lagrangian relaxation and primitive dual problem decomposition method respectively. According to the simulation results, the proposed content delivery algorithm can reduce the system transmission cost and improve the local cache hit rate efficiently.