A matrix metalloproteinases (MMPs) triggered multifunctional micellar system loading traditional chemotherapeutic agent paclitaxel (PTX) and marimastat (MATT), an inhibition of matrix metalloproteinases, was established to prevent tumor growth and metastasis. The micelles were self-assembled by the conjugate synthesized with an MMPs sensitive peptide as the bridge between PTX and poly(ethylene glycol) (PEG). 4T1 cell line derived from a murine breast tumor was selected as the cell model due to its high metastasis. The cytotoxicity assay and cell apoptosis analysis revealed that the sensitive micelles increased the toxicity and cell apoptosis compared with the insensitive micelles. In addition, this system also exhibited high penetration ability in tumor spheroids and significant invasion inhibition with the method of Transwell invasion assay. In the BALB/c mice bearing 4T1 tumors, this system inhibited the growth of the metastatic tumor and prevented the incidence of lung metastasis with low systemic toxicity. And the expression of MMP-2 and MMP-9, which are important in the process of tumor metastasis, was down-regulated. Generally, the data obtained from the in vitro and in vivo studies confirmed that the codelivery of PTX and MATT by the MMPs sensitive micelles achieved not only significant antitumor effect but also obvious inhibition effect of tumor metastasis, which are the leading cause of cancer deaths. This functional particle system may provide a promising strategy for metastatic breast cancer therapy. (C) 2018 Published by Elsevier B.V.