The plum (P. domestica L.) is a hexaploid fruit tree species cultivated around the world. In Algeria, dried plums are used in traditional dishes, being popular in rural areas, and are also eaten fresh or processed as jam. Despite its socio-economic importance, its varietal diversity remains unknown, which led us to launch a phenotypic characterization of plum (P. domestica L.) accessions in western Algeria. Our first step was to conduct a field survey in western Algeria using a questionnaire and collect plant material from 16 regions of seven different wilayas. We utilized 35 morphological and pomological characteristics suggested by UPOV, and the data were used to describe the different varieties and were exploited in different analyses (ANOVA, Multiple Component Analysis (ACM), and Principal Component Analysis (PCA)), indicating a distinct difference between the accessions. An important phenotypic variance was recorded for the studied characteristics, such as the length, width of the leaves and flower petals, ripening period of the fruit, and size and weight of the fruit, which aids us in identifying three major groups independent of their geographical origin. Identifying the plum cultivars used in breeding programs has led to the valorization and preservation of this valuable genetic resource.