This paper investigates the content placement problem to maximize the cache hit ratio in device-to-device(D2D)commu-nications overlaying cellular networks.We consider offloading contents by users them-selves,D2D communications and multicast,and we analyze the relationship between these offloading methods and the cache hit ratio.Based on this relationship,we formulate the content placement optimization as a cache hit ratio maximization problem,and propose a heuristic algorithm to solve it.Numerical results demonstrate that the proposed scheme can outperform existing schemes in terms of the cache hit ratio.