Abstract: CG approximation and LS approximation associated with narrow band model can be utilized to deal with radiation heat transfer problem in non-gray,non-isothermal and inhomogeneous media.Therefore,they are broadly adopted in studying high-temperature gas radiation transfer problem in engine combustor and plume of high speed flying vehicles.Carbon dioxide is a primary combustion product of carbonaceous propellant and the close attention has been paid on studying its radiative properties.But some of today's narrow band model parameters are obtained by fitting to experimental data and the spectral resolution is too low;some could not overlay near,middle and far infrared spectral region,or precision of some parameters is too bad;particularly high temperature data of over 2000 K are lacking.In this paper,by making use of the up-to-date high resolution and high temperature flame gas spectral database-HITEMP (serial number:3153),and parameters such as line strength,self-broaded half-width,and air-broaded half-width in HITEMP database being extrapolated to 300～3000 K,new carbon dioxide parameters,such as mean absorption coefficient,line density and mean half-width are obtained.Based on these parameters and narrow band model,the emissivity and transmissivity are evaluated under different temperature,pressure and optical path conditions.Results show a good agreement with Scutaru,Ferriso,Ludwig's experimental values.