Abstract: For taking a new road to industrialization and building a completely well-off society，the development of the primary industry is more highlighted and a large number of agricultural clusters are developed in current China. At present，more and more attentions has been paid on the study of industrial cluster，while theoretical study on it is relatively less，and the practice of agricultural industry cluster has been beyond theoretical researches. Therefore，it is of great theoretical and practical significance to analyze China’s agricultural industry cluster. Based on previous research，the theory of domestic and international research of agricultural industry cluster，using secondary data and semi-structured interviews，the paper took medlar products processing industry in Zhongning County，Ningxia Province，China as a case to study the formation mechanism of agricultural industry cluster，the stages of development，in order to provide theoretical guidance and reference for the development of China’s agricultural industry cluster. The results show as follows：（1）Cluster evolution stage of the county can be divided into the cultivation period，growth stage and formation stage，development stage，and the clusters in different stages showed different characteristics. （2） It is the stochastic factor （including macro system，resources endowment，and regional culture，etc） that induced the rise of medlar products processing industry in Zhongning County. A large number of enterprises agglomeration leads to the regional specialization of production，pullulate industry cluster. Increasing return and path dependence are the mechanism that has important influence on the rapid development of clusters. But in course of the rapid development of clusters，specialized regional milieu （government management，labor，market capacity） plays an important role，too. （3） There is a big problem which cannot be ignored，as the benefit increasing，path dependence，and enterprise traditions，the cluster could be locked in the low-efficiency situation. To eliminate this kind of situation，measures of attracting high-level talents and enterprises to settle down in the cluster，promoting the cooperation strengths between enterprises，enhancing the quality and heterogeneity of knowledge and accelerating knowledge transfer within the cluster to uplift the innovation capability of the “clusters”. On the other hand，it is important to utilize the development opportunity of “Ningxia Inland Economic Experimental Zone”，by means of widening the existing enterprise organization boundary，re-allocating new global resources，and expanding new market to keep the sustainable competitiveness of industrial clusters.

Key words: agricultural industrial cluster, evolution stage, mechanism analysis, medlar, Zhongning County