Objective: This study aims to analyze the reasons why freeze-drying affects the survival of Lactobacillus paracasei PC-01 cells from the perspective of proteome. Method: Set different fermentation temperatures to 32.5 ℃ and 37 ℃， respectively， high-density fermentation of Lactobacillus paracasei PC-01 and freeze-drying， taking samples before and after freeze-drying， using TMT technology for protein quantitative determination， KEGG function annotation and enrichment analysis were performed on the identified differential proteins， and the mechanism of the differential expression of the proteins on the survival of the bacteria in the two experimental groups was studied. Result: The experimental results showed that the number of viable bacteria before and after freeze-drying of the high-density fermentation of Lactobacillus paracasei PC-01 at 32.5 ℃ was significantly higher than that of the 37 ℃ experimental group. The study found that the up-regulated proteins were concentrated in carbohydrate metabolism and membrane transport. In terms of pathways， the proteins with large differences before and after freeze-drying are aldehyde ketone reductase， 4-oxalocrotonic acid tautomerase， dipeptidase， GNAT family N-acetyltransferase， phosphoribosylglycinamide formyl proteins such as transferase. Conclusion: The development of this research has enabled us to understand the changes in the internal molecules of Lactobacillus paracasei PC-01 before and after freeze-drying. According to the functions of key differential proteins， freeze-drying mainly affects freezing resistance， membrane transport capacity and cell metabolism. The cells of Lactobacillus paracasei PC-01 strain survived. This can provide a reference for the industrial production of Lactobacillus paracasei PC-01.