The lactobacillus with high N-nitrosamine-degrading ability was screened from 16 strains of lactobacillus isolated from traditional fermentation products in Inner Mongolia by high performance liquid chromatography which was used to detect the content of N-nitrosamine in the co-culture system of lactic acid strain and N-nitrosamine， and its degradation characteristics and mechanism were revealed. The study showed that L.plantarum AL6-1 could efficiently degradate N-nitrosamines， and the degradation effect could be improved when the incubation time was 36 h， the initial pH was 4.5， the temperature was 37 ℃ or the inoculation concentration was 1010 CFU/mL in the culture system with the final concentration of N-nitrosamines of 1 μg/mL. The maximum degradation effect of N-dimethylnitrosamine and N-diethylnitrosamine was 63.90% and 61.65%， respectively. And the degradation rate of L.plantarum AL6-1 intracellular extract on NDMA and NDEA reached 70.28% and 71.88%， respectively， within 6 hours. It was determined that the removal of nitrosamines was mainly through the degradation of intracellular extract.