Pea is one of the earliest domesticated crops. It is not only an important economic and grain-vegetable-forage crop widely grown globally, but also has significant ecological advantages in the sustainable development of agriculture. This article reviews the important research progress of the past decades in the aspects of the domestication of pea, systematic classification of Pisum, preservation status and research and utilization of germplasm resources of pea and its wild relative. Although there have been many studies, the domestication process of pea is still unclear and the systematic classification of Pisum has long been controversial. Combining the previous different classification views, phylogenetic research results, as well as our current research results, this article puts forward a comprehensive classification proposal on Pisum to make clear about pea wild relatives, thereby laying a foundation to better understanding of the domestication process of pea and make full use of the germplasm resources of pea wild relatives. In addition, in view of the current research status of pea wild relatives, relevant suggestions are made for their future research, so as to give full play to their huge potential in breeding improvement of pea.