Metal 3D printing technology using an arc energy source—widely known as wire arc additive manufacturing (WAAM)—has a great promising for manufacturing large-sized and medium–complex parts. However, with its very large heat input characteristics, the complex thermal cycle and heat accumulation cause major challenges in WAAM. This paper presents a short review on the influence of heat accumulation on the process stability, geometric accuracy, and material properties. In addition, methods for reducing the heat accumulation phenomenon to improve the product quality are also exported. The findings reveal that the heat buildup is one of the most important causes that leads to low surface quality, high thermal distortion, and high residual stress. The heat accumulation also causes anisotropy in microstructures and materials properties. The paper provides an insight into the WAAM process, especially on the heat buildup phenomenon and several methods to reduce such a phenomenon and improve the quality of WAAMed parts.