〔Abstract〕 Objective To investigate the expression of lysophosphatidic acid(LPA) in mouse silicosis model and its effect on epithelial-mesenchymal transition(EMT) of mouse lung epithelial(MLE-12) cells. Methods 20 C57 BL/6 male mice were randomly divided into the control group and the model group. The control group was given normal saline, and the model group was given nasal drip of 50 μl silicon dioxide(SiO2) suspension with 100 mg/L every day for 7 consecutive days. They were killed on the 28 th day. Partial lung tissues were taken. Immunohistochemistry was used to observe the expression of lysophosphatidic acid receptor 1(LPAR1), and Western blot was used to detect the protein expression of α-smooth muscle actin(α-SMA),Type Ⅰ collagen( COLⅠ) and LPAR1; the proliferation of MLE-12 was detected by solution cell proliferation assay; scratch test was used to detect the migration ability of SiO2on MLB-12 cells. MLE-12 cells were divided into control group, SiO2stimulation group and inhibitor group, and the expression levels of LPARI and EMT related proteins were detected by Western blot. Results Western blot detection showed that the expression of α-SMA and COLⅠin the lung tissue of mice from the model group increased, and the model was established successfully; immunohistochemistry showed that the expression of LPAR1 was positive in the epithelial cells around the trachea and bronchus of the model group mice, showing bright brown; Western blot detection found that the expression of LPAR1 protein in the lung tissue of mice from the model group was higher than that from the control group(P<0.05); cell proliferation assay and scratch test showed that SiO2could significantly promote the proliferation and migration of MLE-12 cells; Western blot showed that the expression of LPAR1 and interstitial marker Vimentin protein increased in SiO2stimulation group(P<0.05), while the expression of epithelial marker E-cadherin protein decreased(P<0.05), and the difference was statistically significant compared with the control group and the inhibitor group(P<0.05). Conclusion The expression of LPA increased in mouse silicosis model, which can promote the proliferation and migration of MLE-12 cells by regulating EMT process and exacerbates the process of silicosis in mice.