A Combined Atmospheric Radiation Transfer (CART) software was developed, which could be used to calculate the spectral transmittance and background radiation (including ambient scattered solar radiation and thermal radiation) of the atmosphere from visible to far infrared wavelength bands based on atmospheric parameters. The multi-dimensional variations of atmospheric transmittance and background radiation in a certain wavelength-band with zenith angle and distance were paid special attention by researches in optical engineering area. Thus, it was necessary to quickly calculate the scene atmospheric optical characteristics. The newly two-dimensional scene fast computing function of atmospheric radiative transfer by using CART was mainly introduced. According to the characteristics of discrete coordinate method (DISORT) which could simutaniously output the radiance at various zenith angles and azimuth angles, the program to calculate the multiple-scattered atmospheric radiance was designed at each direction (azimuth and zenith angles) simultaneously, which greatly improved the calculation efficiency. As the atmospheric transmittance and heat radiation change slowly with space position, sampling calculation and spline interpolation were adopted to save the calculation time greatly while keeping the calculation accuracy. For a scene with more than 10000 times calculations, the speed was 2-3 orders of magnitude faster than before. It will be usefull in the calculation of atmospheric radiative transfer scenarios in practical engineering applications.