The overexpression of P-glycoprotein (P-gp) on cell membrane is one of the most important reasons for multidrug resistance (MDR) in cancer. Multifunctional drug delivery systems could only reverse MDR to some extent through bypassing the drug pump mediated by P-gp. It has been reported that trametinib could selectively inhibit the function of P-gp. However, there are no reports on the use of trametinib combined with drug delivery systems to reverse MDR at present. In this study, we constructed two types of drug delivery systems (H-F-DOX NPs and H-F-Tat-DOX NPs) based heparin as backbone with folate and cell penetrating peptide Tat for achieving active targeting. The results indicate that trametinib could enhance the cellular uptake of multifunctional drug delivery systems on drug-resistant cancer cells by specifically inhibiting the function of P-gp, change the endocytic pathway of drug delivery systems and release doxorubicin into the nucleus to kill drug-resistant cells, paving a