In recent years, network function virtualization has attracted massive attention in academia and industry,and the virtual network functions placement problem is one of them. Reinforcement learning has been widely applied in network control and decision, which can learn the optimal policy according to the environment feedback automatically. This paper presents a new summary of the virtual network functions placement problem based on reinforcement learning. We will give a detailed description of how to use reinforcement learning to solve virtual network function placement in different scenarios, then the prospect of further research is forecasted preliminarily.