Abstract: Objective: To investigate the heterogeneity of hepatocytes and non-parenchymal cells [hepatic stellate cell (HSC), liver sinusoidal endothelial cell (LSEC)] during the progression of liver f ibrosis, as well as the intercellular interactions mediated by secreted phosphoprotein 1 (SPP1) among the above cells. Methods Single-cell RNA sequencing data of liver tissues from 6 mice (3 normal control mice and 3 CCl4-induced liver f ibrosis model mice) were obtained from the NCBI GEO database. Total of 87 552 cells were obtained after cell alignment and quantif ication by Cell Ranger and Seurat quality control (excluding lowquality cells, doublets, and cells with mitochondrial gene ratio ＞ 15%). Dimensionality reduction was performed using principal component analysis (PCA) and uniform manifold approximation and projection (UMAP), followed by Louvain clustering and Wilcoxon test to screen for dif ferentially expressed genes (|log2FC| ＞ 2, adjusted P ＜ 0.05). GO enrichment analysis and CellChat ligand-receptor analysis were performed on the dif ferentially expressed genes. Results Compared with the control group, the number and proportion of f ibroblasts in the CCl4 group were signif icantly increased (absolute increase of 5.6%～12.4%, all P ＜0.001), while the proportion of hepatocytes was decreased. The expression of f ibrosis markers, including Acta2, Col1a1 and Col1a2, was upregulated. A total of 2 132, 1 281, and 308 differentially expressed genes were identif ied in hepatocytes, HSC and LSEC, respectively, among which SPP1 was signif icantly upregulated in all three cell types (log2FC = 5.47, 6.08 and 6.78, respectively). Fifty-six genes were co-upregulated across the three cell types and were enriched in pathways related to inflammation, adhesion and extracellular matrix synthesis. Protein-protein interaction network showed that SPP1 occupied a central position. Cell-cell communication analysis indicated that the interaction between activated HSC and M2 macrophage was the strongest, and SPP1 signaling mainly originated from activated HSC and macrophage. Through cluster analysis, hepatocytes were divided into 7 subclusters (Cluster 0～6), among which Cluster 1 (accounting for 21.6%) had an average SPP1 expression level (8.09) that was 5.7～80.9 times that of the other clusters, and also showed high expression of Acta2, Col1a1, and Col3a1. Activated HSC were divided into 6 subclusters (Cluster 0～5). The average SPP1 expression level (3.16) in Cluster 1 (accounting for 33.6%) was 1.3～27 times that of the other subclusters. LSEC were divided into 6 subclusters (Cluster 0～5). Cluster 1 had the highest average SPP1 expression level (3.38), followed by Cluster 2 (2.06) and Cluster 5 (1.15). Moreover, Cluster 2 and Cluster 5 highly expressed pro-f ibrotic markers. Conclusion SPP1 might act as a key hub regulating the synergistic promotion of liver f ibrosis progression by hepatocytes, HSC and LSEC.