The mobile opportunistic network is an emerging thread of mobile and wireless networks, which distributes messages when nodes move and encounter with others over infrastructure-less networks. Network topologies in such networks can be fragmented dynamically, and end-to-end paths between any pairs of source and destination cannot be guaranteed. Many studies resort to delay-tolerant, store-carry-and-forward transfer model to deliver messages. However, without regard to contact relationship among nodes, those efforts are sensitive to node mobility and network dynamics. In this paper, we propose a new routing scheme, named Temporal Periodicity for Message Delivery (TPMD). We identify the characteristic of contact periodicity among nodes in a temporal scale, and formulate a period quantification procedure. As a result of temporal periodicity in mobile opportunistic networks, we conduct simulation to examine TPMD and show its efficiency on improving successful delivery rate and lowering message overhead as compared with the famous PRoPHETv2 scheme.