Wire arc additive manufacturing (WAAM) is a kind of additive manufacturing technology with excellent development potential in recent years. This work aims to summarize the current research status and challenges in WAAM and provide quality improvement methods. The research status of WAAM in surface finish and forming accuracy, microstructure and mechanical properties, residual stress and deformation, porosity and other defects is given. The methods of eliminating the above shortcomings and improving the microstructure and mechanical properties are summarized from pre-processing, on-line processing and post-processing perspectives. It is concluded that there are still many challenges to the widespread adoption of WAAM, and various perspectives may be needed to achieve this. The development of path planning and slicing algorithm, the combination of online monitoring systems with existing WAAM equipment, and composite post-processing technology will be the key research directions in the future.