Dynamic graphs are ubiquitous in the real world, yet there is a lack of suitable theoretical frameworks to effectively extend existing static graph models into the temporal domain. Additionally, for link prediction tasks on discrete dynamic graphs, the requirement of substantial GPU memory to store embeddings of all nodes hinders the scalability of existing models. In this paper, we introduce an Input {\bf S}napshots {\bf F}usion based {\bf Dy}namic {\bf G}raph Neural Network (SFDyG). By eliminating the partitioning of snapshots within the input window, we obtain a multi-graph (more than one edge between two nodes). Subsequently, by introducing a graph denoising problem with the assumption of temporal decayed smoothing, we integrate Hawkes process theory into Graph Neural Networks to model the generated multi-graph. Furthermore, based on the multi-graph, we propose a scalable three-step mini-batch training method and demonstrate its equivalence to full-batch training counterpart. Our experiments, conducted on eight distinct dynamic graph datasets for future link prediction tasks, revealed that SFDyG generally surpasses related methods.