With the development of knowledge graphs, utilizing given knowledge graph data to automatically obtain answers to human natural language questions has become popular in recent years. QA systems such as Siri and Xiao Ai have been widely used. Thanks to the introduction of deep learning, breakthroughs have been made in various sub-projects in this field, but there are still difficulties that need to be overcome, such as multi-hop reasoning and strategy combination. Therefore, starting from the mainstream construction method, this study summarizes the current research status and challenges in this field, which can not only help researchers to efficiently carry out research in this field but also help researchers in different industries to develop industry-related QA systems to improve productivity.