Abstract: The rapid development of the aerospace industry has put forward higher demand for high-strength and lightweight Al alloy materials. However, due to the physical characteristics of these alloys, it is difficult to prepare welding wires. Therefore, the synthesis of target alloy materials using multi-wire arc additive manufacturing (WAAM) has attracted more and more scholars' attention. Furthermore, in order to obtain products with uniform microstructure and stable performance, it is also a major difficulty to regulate and control the additive manufacturing process through online monitoring.The efforts made by many scholars in process inspection and control, droplet transfer control and microstructure in recent years were introduced.The existing problems and challenges of multi-wire arc additive manufacturing were summarized.The future research objectives and development prospects were also analyzed.