Objective: To study the expressions of CD147and MMP9 in the lung metastasis model of breast cancer in BCML-TAII99 mice and their correlation with tumor growth and metastasis thereof. Methods: The breast cancer model with lung metastasis was established in BCML-TAII99 mice. The immunohistochemical staining method(SP method) was used to analyze the expressions of CD147 and MMP9 in mice lung metastasis tissue. The relationship between the tumor growth and the metastasis was analyzed. Results: The positive rates of CD147 and MMP9 were 63.33%（19/30）and 53.33%（16/30）respectively in mouse models. There was significant difference in positive rate of expressions between the metastasis group and the non-metastasis group（χ~2= 6.238， P ＝ 0．013； χ~2＝ ＝5．129， P ＝ 0．024). There was a statistically significant positive correlation between the expression of CD147 and MMP9（r = 0．786， P ＝ 0.025). Conclusion: The expression of CD147 may play a crucial role in infiltration and metastasis of breast cancer by inducing the expression of MMP9.