Abstract: Objective To discover the inhibitory effect of Doxycycline on invasion of Human colorectal carcinoma LS174T cells in vitro.Methods Artificial recombinant basement membrane invasion assay was utilized through Transwell model.Zymography was used to observe the decrease of MMP2.Results Doxycycline could inhibit the invasion of human colorectal carcinoma LS174T cells in vitro.With 5mg/L, 10mg/L and 20mg/L Doxycycline, the number of cells which could invaded through the Matrigel was respectively 101.3±6.7, 83.7±5.7 and 42.0±2.0.The inhibition ratio was respectively 17.9%, 32.0% and 65.9%, dose-dependently.Under 5mg/L, Doxycycline could decrease the secretion of MMP-2.Conclusion Doxycycline had inhibitory effect on invasion of colorectal carcinoma LS174T cells through inhibition of the secretion MMP-2 under a low dose.Doxycycline was a potential agent inhibiting tumor invasion and metastasis.