The effects of mass fraction and particle size of 1,1-diamino-2,2-dinitroethylene(FOX-7),different composite combustion catalysts with lead, copper and carbon on the combustion performance of nitrocellulose (NC)/trimethylotethane reinitiate(TMETN） low-insensitive and smokeless composite modified double base(CMDB) propellant with screw extrusion process were investigated by means of strand burner method. The results shown that the burning rate of CMDB propellant is first rise and then descend with the addition of FOX-7. When the FOX-7 content is 25%,the burning rate of CMDB propellant rised from 5.87 mm·s^-1 to 14.90 mm·s^-1 at 10 MPa, and when the content of FOX-7 increases from 25% to 30%, the burning rate decreased from 14.90 mm·s^-1 to 12.78 mm·s^-1 at 10 MPa. The pressure exponent of burning rate between 6-16 MPa decrease from 0.97 to 0.60 as the mass fraction of FOX-7 in the formulation increased from 5 % to 30 %. When the FOX-7 be replaced by finer particles FOX-7 with the same mass, the burning rate decreased 1.16 mm·s^-1 at 10 MPa, while the pressure exponent of burning rate between 6-14 MPa increased. The burning rate of propellant with addition of β-Pb/β-Cu/CB combustion catalyst increases from 14.90 mm·s^-1 to 18.65 mm·s^-1 at 10 MPa, while the pressure exponent of burning rate between 6-16 MPa decrease from 0.63 to 0.35, which compared with the referenced formulation (no combustion catalyst).