Abstract: The content variation of intracellular free amino acid,organic acid and protein of Lactobacillus plantarum dy-1(L. P. dy-1)were determined. Then the matebolic characteristic of freeze-dried L. P. dy-1 during fermentation affected by different cryoprotectant were compared and studied. The results were as follows:the total amino acid content of activation bacteria group was 625.23 μg/100 μL,and the content of freeze-dried group protected by 10% inulin was increased to 753.72 μg/100 μL,while the amino acid of 22.4% inulin group,inulin composite protective agent group and skim milk composite protective agent group decreased. The total organic acid content of activation bacteria group was 62.84 mg/L,while the content of the freeze-dried bacteria with cryoprotectant decreased significantly. Among them,the total organic acid of inulin composite protective agent group with the content of 52.99 mg/L was most similar with the activation bacteria group. The mycoprotein SDS-PAGE patterns of the freeze-dried bacteria with different types of inulin cryoprotectant were similar,and there was no significant difference with the activation bacteria group. Otherwise,the pattern of the skim milk composite protective agent group was different from the activation bacteria group,which was lack of more electrophoretic bands and the content was less than the other groups. The results indicated that the addition of inulin,especially the inulin composite protective agent would make the metabolic characteristic of freeze-dried L. P. dy-1 more close to the normal group.