Near-infrared spectra of lightning return strokes are obtained by Slit-less infrared spectrograph in Shandong region.Compared with the visible spectrum of lightning return strokes,the radiation order of lighting plasma is analyzed,and the main radiation mechanism of continuum spectra in the two wavelength range are also discussed.The obtained results show that:the visible spectrum of lightning is mainly radiation from early stages and development of lightning,and the line spectra of ionizing nitrogen and oxygen is the main spectra of the separation spectrum; the near-infrared spectrum is mainly radiation from the latter of the lightning, and the line spectra of neutral nitrogen and oxygen atoms is the main spectra of the separation spectrum; the visible spectral band is mainly from bremsstrahlung contribution and the infrared part of the continuous spectrum is mainly from the recombination radiation; loss of a photon for the free electronic of high-temperature and other energy particle collisions of the lightning plasma is the main course of bremsstrahlung process,there are a lot of free e-collision,the lightning channel gathered in a large number of neutral atoms,molecules,electronics,and with the positively charged ions (including N++,N+,N*,N,O++,O+,O*,O particles,etc.),thus forming a typical plasma channel; atmospheric ions and free electrons of the dissociation process and the positive ions and negative ion radiation process is the direct radiation of the two main ways.It is deduced from the results that the recombination in lightning plasma is the main process for lightning producing O3 and NOX,the sorption and desorption of oxygen during the recombination may be the main reason for increased lines of oxygen atom in near-infrared spectra,and also for relative strength of OI 777.4 nm that is larger than normal.