The mechanical properties, sensitivity and compatibility of polyethylene glycol (PEG)/nitroglycerin (NG)/trimethylolethane trinitrate (TMETN) blends were studied by molecular dynamics and mesoscopic dynamics simulations. The designed systems included PEG/NG、PEG/TMETN and PEG/NG/TMETN, in which the mass ratios of NG to TMETN were set to be 3∶1, 1∶1 and 1∶3, respectively. The PEG/TMETN blends have the best mechanical properties, lowest sensitivity and best compatibility. Considering the energy of TMETN was lower than NG, the mixed plasticizer " NG/TMETN" was a nice choice which combined "the high energy of NG" and " the excellent performance of TMETN". Specifically, the addition of TMETN into the PEG/NG blends resulted in the reduced sensitivity of the blends, the crystallinity of PEG and the self-aggregation of NG will be suppressed, together with improved compatibility. Although the mechanical properties of the PEG/NG/TMETN blends were slightly worse than these of the systems with single plasticizer, the properties can be improved by increasing the content of TMETN (NG∶TMETN=1∶3). The processability of PEG/NG/TMETN was good. The mechanical properties of the mixed plasticizer system were related with hydrogen bond, while the properties of single plasticizer systems were more affected by the nature and structure of the substance. The thermal sensitivity of the mixed plasticizer systems can be characterized by maximum length of trigger bond or cohesive energy density.