The effects of 3,4-dinitrofurzanfuroxan (DNTF) contents on dynamic mechanical properties of modified double-base propellants (DNTF-CMDB, DF) were studied by dynamic mechanical analyzer (DMA). The characteristic values of dynamic mechanical properties at multi-frequency for DF propellants were obtained. Results show that two β-relaxations, besides a α-relaxation, appear on DMA curves of DF propellants, and β₁-relaxation is due to the effect of DNTF. It is shown that the DNTF content can obviously affect the dynamic mechanical properties of DF propellants. The correlations between the tanδ peak temperature T_α in the α -relaxation, the free volume expansion coefficients α_f of α -relaxation and β-relaxation and the sum of ratios NG/NC and DNTF/NC were obtained. The DF propellants with 20% DNTF have optimal mechanical properties at high and low temperatures.