The invention provides a lactobacillus plantarum LN66 and an application thereof to a product reducing a halitosis risk and relates to the technical field of halitosis prevention and treatment. An LN66 strain is preserved with the number of CGMCC No. 17369. The LN66 strain is directly separated from a healthy human body, is a Gram staining positive bacillus, is incapable of generating spores and is capable of growing in both aerobiotic and anaerobic environments. The LN66 strain has good tolerance to lysozyme and adapts to the oral environment, not aims at killing fusobacterium nucleatum, butaims at reducing the occurrence and development risks of halitosis by reducing the expression level of genes relevant to the formation of a biological film in the fusobacterium nucleatum, reducing thesecretion of extracellular polymeric substances (EPSs) of the fusobacterium nucleatum and specifically inhibiting or reducing the formation of fusobacterium nucleatum biological films.