Abstract: Lactobacillus paracasei L1 was the dominant Lactobacillus isolated from naturally fermented sweet potato sour slurry and its safety and probiotics were evalualed. The safety of Lactobacillus paracasei L1 was evaluated by drug resistance test,harmful metabolites test and animal experiment. The probiotics of Lactobacillus paracasei L1 was evaluated by environmental tolerance and physiological function test. The results showed that the bacteria was resistant to erythromycin and azithromycin,sensitive to penicillin,insensitive to other antibiotics and without plasmid,the results of toxic metabolites test were negative and hemolysis did not occur,all life activities of mice were normal during 7 and 30 days of feeding,indicating that the bacteria did not cause acute toxicity and subchronic toxicity. The total viable bacteria count of L1 was always above 10⁷ CFU/mL in acidic and biliary environments,and the total viable bacteria count of L1 was always above 10¹⁰ CFU/mL in high salinity environments,the self-aggregation of L1 was 15.8%±1.2% in 1 h incubation,the hydrophobicity of L1 was 9.7%±0.8%,and the adhesion rate to Caco-2 cells was 22.37%±1.44%. It could be concluded that Lactobacillus paracasei L1 has good safety and probiotics,which laid a foundation for the production of safe and healthy flocculant of sweet potato starch and provided scientific basis for practical production and application.