The invention discloses Weissella sinus with broad-spectrum antibacterial activity, and belongs to the field of microorganisms. The strain is preserved in the China Center for Type Culture Collection, the preservation number is CCTCC NO: M 20211696, the preservation address is Wuhan University, Wuhan, China, and the preservation date is December 29, 2021. The Weissella cibaria BYL4.2 disclosed by the invention is separated from pickles, and experiments prove that the Weissella cibaria BYL4.2 can inhibit growth and reproduction of penicillium chrysogenum, aspergillus versicolor, escherichia coli, staphylococcus aureus, listeria monocytogenes and pseudomonas aeruginosa in vitro, and has broad-spectrum antifungal and bacterial activity; moreover, the compound is sensitive to antibiotics such as erythromycin and rifampicin, is relatively high in safety, is high in survival rate in gastric acid and intestinal high-bile-salt environments, and has potential application prospects in the fields of improvement of the intestinal environment and preservation and fresh keeping of foods.