Based on the classification of spare parts and the research results of the demand of spare parts, a three-dimensional classification model of spare parts of agricultural machinery is established, which includes the application axis sorted by technical characteristics, the cost axis classified by ABC method, and the demand axis classified by the demand of the spare parts of agricultural machinery. These dimension axes represent different factors, and the application of factors in purchase is analyzed. Guiding value of each dimension axis is summarized in the field of the spare parts purchase; and corresponding strategy instruction is put forward. Integrated application of these strategies by model makes the purchase have more realistic operational meaning. Application field of the three-dimensional model of spare parts is discussed; and the direction for further research is pointed out.