Molecular spectral parameters are fundamental data for IR radiation calculation. Currently, there is no such gas spectral database as the high resolution transmission molecular absorption database (HITRAN database) in China. In this paper, supported by the National Numerical Windtunnel (NNW) project, we developed the calculation codes of high-temperature air spectral parameters to support the calculation of target IR radiation. To be specific, NO is one of the products of chemical reactions in the high-temperature air flow field of hypersonic vehicles, and the radiation generated by its vibration-rotation levels is in the typical band of infrared detectors. Based on the molecular potential and permanent dipole moment of split NO calculated by the ab initio method, we calculated the line intensity of NO at 8000 K, and the theoretical calculation results were in a good agreement with the values from the HITRAN database at 300 K and 3000 K. Moreover, we calculated the absorption coefficient of NO at the X ²Π_1/2 state at 296 K and 2000 K by employing the narrow-band model. It turns out that without the help of experimental spectral constants, the proposed method can obtain more line positions than the HITRAN database in both low and high vibration levels, which can provide the high-temperature spectral data of NO for the calculation of target radiation characteristics in the NNW project.