Software-defined Network (SDN) is considered as a promising technology to provide a flexible network for 5G. However, as the resource of flow entries in switches is limited in SDN, a novel flow management method is required when facing massive amounts of IoT devices. To the best of our knowledge, existing methods designed for IoT can only be applied to uncomplicated network environments without multiple periodic traffic flows. In this paper, we propose Periodic Subflowbased Proactive Flow Installation Mechanism (PSPFIM), a more widely applicable method with better performance. Compared to related works, we improve the hit ratio by 45% and installation efficiency by 6.19 times according to results of simulations, which means PSPFIM can reduce the average network latency with even less flow entries.