In the research of near-infrared spectroscopy (NIRS) qualitative analysis technology, the experimental objects mainly include liquid matter, powder matter and non-uniform solid particles. The liquid and powder materials are evenly distributed, and the spectrum collection and analysis are relatively easy. The non-uniform solid particles are different in size, shape and internal material distribution. Near-infrared spectroscopy of these samples contain the type information to be extracted in qualitative analysis and the individual difference information to be eliminated. Therefore, the analysis of non-uniform solid particles is more difficult than that of liquid or powder materials with uniform distribution. At present, there is no effective NIRS qualitative analysis method for non-uniform solid particles with different sizes and shapes at home and abroad. In this paper, non-uniform solid grain maize is taken as the research object. Based on the study of various spectral acquisition methods, the characteristics of non-uniform solid grain spectral acquisition are analyzed, and the spectral acquisition device for non-uniform solid grain is designed. In order to ensure the objectivity of the experimental results, Five pattern recognition methods such as Naive Bayesian classifier, k-nearest neighbor, support vector machine, BP neural network and Biomimetic Pattern Recognition were used to establish the qualitative analysis model of single grain maize by near-infrared spectroscopy in diffuse reflection and diffuse transmission mode, and the qualitative analysis models established in diffuse reflection and diffuse transmission mode were compared to analyze the effect of embryo orientation on the identification of single grain maize. The effect of the time interval between train and test sets on the identification accuracy under diffuse reflection and diffuses transmission is studied too. The experimental results show that the diffuse transmission model is not easily affected by the lying style of non-uniform solid grains, and the model has better generalization ability, which provides a feasible spectral acquisition method for subsequent research. Taking the non-uniform solid maize grain as the main experimental object, the research on its collection method and qualitative analysis model can provide a useful reference for the qualitative analysis of near-infrared spectroscopy of similar objects, which has important research significance.