Breast cancer (BC) is one of the most common malignant tumors in women. Angelica sinensis polysaccharide (ASP) is one of the main components extracted from the traditional Chinese medicine Angelica sinensis. Research has shown that ASP affects the progression of various cancers by regulating miRNA expression. This study aimed to explore the specific molecular mechanism by which ASP regulates BC progression through miR-3187-3p. After the overexpression or knockdown of miR-3187-3p and PDCH10 in BC cells, the proliferation, migration, invasion, and phenotype of BC cells were evaluated after ASP treatment. Bioinformatics software was used to predict the target genes of miR-3187-3p, and luciferase gene reporter experiments reconfirmed the targeted binding relationship. Subcutaneous tumor formation experiments were conducted in nude mice after the injection of BC cells. Western blot and Ki-67 immunostaining were performed on the tumor tissues. The results indicate that ASP can significantly inhibit the proliferation, migration, and invasion of BC cells. ASP can inhibit the expression of miR-3187-3p in BC cells and upregulate the expression of PDCH10 by inhibiting miR-3187-3p. A regulatory relationship exists between miR-3187-3p and PDCH10. ASP can inhibit the expression of β-catenin and phosphorylated glycogen synthase kinase-3β (p-GSK-3β) proteins through miR-3187-3p/PDCH10 and prevent the occurrence of malignant biological behavior in BC. Overall, this study revealed the potential mechanism by which ASP inhibits the BC process. ASP mediates the Wnt/β-catenin signaling pathway by affecting the miR-3187-3p/PDCH10 molecular axis, thereby inhibiting the proliferation, migration, invasion, and other malignant biological behaviors of BC cells.