Several laboratory scale research on nitrate ester plasticized polyether (NEPE) solid propellants with and without ammonium dinitramide (ADN) and N-guanylurea-dinitramide (GUDN), featured with the same nominal composition, have been prepared and evaluated. The combustion properties (strand burn rate and flame photos) and thermogravimetry (TG) analysis of propellants with ADN and GUDN have been determined. These parameters are compared to those of reference blank compositions. It turns out that the ADN/GUDN dual oxidizer may greatly affect the combustion behavior of NEPE propellants. The addition of ADN particles to the propellant formulations can increase the burn rate and pressure exponent (n), when a fracture of AP or GUDN was replaced by ADN, the n increases from 0.52 to 0.67 and from 0.58 to 0.67, respectively. By replacing AP flakes with the same fraction of GUDN, the burning rate decrease by 18.97% at 7.0 MPa and n increased by 12.04% (1-15 MPa), in comparison to the reference propellant. The involved NEPE propellants with and without ADN/GUDN dual oxidizers at various pressure ranges show multi-flame structure, and the brightness of flame increases with the pressure increases. Addition of ADN can decrease the thermal decomposition temperature. Moreover, when part of AP was replaced by GUDN, the thermal decomposition procedure is close to that of the reference sample.