Abstract： Objective:To study the dynamic changes of cytokines in bronchoalveolar lavage fluid (BALF) and serum of hard metal lung disease (HMLDR) rats.Methods:In March 2019, the rats were randomly divided into 6 groups, each group included 8 rats: control (C) group include 3 groups, hard metal (HM) group include 3 groups. 10 mg HM were administered in HM group by using the pulmonary endotracheal tube. After 4, 8 and 12 week, the BALF and serum were collected for the enzyme-linked immunosorbent assay (ELISA) of matrix metalloproteinase-1 (MMP-1) , tissue inhibitor of metalloproteinase-1 (TIMP-1) and tumor necrosis factor-alpha (TNF-α) .Results:There was no abnormality in behavior, diet and fur of rats in C and HM group at each exposure time. There was no significant difference in body weight between the two groups of rats ( P>0.05) . Compared with the C group, the expression of MMP-1 in BALF of rats in HM group were significantly higher in all stages (4, 8 and 12 weeks after exposure) ( P<0.05) , the expression of TIMP-1 in BALF of rats in HM group were significantly higher in 8 and 12 weeks after exposure ( P<0.05) . However, there was no significant difference in serum MMP-1 and TIMP-1 levels between the two groups in each stage ( P>0.05) . There was no significant difference in TNF-α. level in BALF and serum between C and HM group in all stages ( P>0.05) . Conclusion:Expression of MMP-1 and TIMP-1 in BALF have reference value in the HMLD auxiliary diagnosis.