To choose the organic material benzamide containing benzene ring and the C-N structure as a model sample, the samples with different nitrogen content were prepared for the Laser-Induced Breakdown Spectroscopy (LIBS) experiment. The experiments were performed under different atmospheres (air and argon) to study the influence of atmosphere on the excitation characteristics of nitrogen in organic materials with different laser energy, then the correlation between nitrogen spectral information and N concentration was established. The results show that, under the air condition, the spectral lines of atomic N of the samples are difficult to be detected, which indicates that the spectral lines of atomic N detected in the atmospheric environmentis mainly from the emision of atomic N contained in air (79% N2 in air). Under the condition of air or argon atmosphere, the molecular CN emission can be both detected and there exists a correlation relationship between the CN emission and N concentration, which is related to the atmosphere and laser energy. Under the conditon of argon, the good correlation relationship exeists both under low and high laser energy due to the formation of CN is from the sample. Under the condition of air, environment there is a good correlation relationship under a lower energy but less under a high energy (R2 higher than 0.9), which indicates that, in air environment, the CN is mainly from the sample under the low energy while the high laser energy causes the formation of CN strongly influenced by nitrogen in the air.