为了进一步探究多重位向关系的自然择优法则，本工作基于以往的实验数据开展系统研究，通过分析不同Mg₂Sn析出相形貌的相变晶体学特征，归纳其共有规律。采用错配较小及匹配矢量较短的晶格匹配判据获得了若干匹配关联矢量对，发现该系统缺少可兼有长度最短和错配最小的矢量对，多重位向关系的共存正是多对匹配关联矢量综合影响的结果。提出以主刻面和次刻面共用的主匹配列为主线的分析方法，发现所有析出相的主匹配列必须平行于位错的短Burgers矢量，除非它平行于不变线或近不变线，揭示了避免长Burgers矢量的位错是约束主刻面及相关位向关系的重要因素。根据主匹配列的结果对位向关系进行分类，不仅完善了对13种位向关系的理解，同时解释了实验中观察到的大多数析出相分布在基体(0001)_α面上的现象。

The orientation relationships (ORs) between precipitates and a matrix are closely related to the precipitate morphology. A deep understanding of morphological crystallography forms the basis for controlling precipitate shapes and provides scientific guidance for improving the strength and plasticity of materials. The coexistence of multiple ORs has been observed in several precipitation systems, providing opportunities to manipulate precipitate morphology. The Mg–Sn-based alloy is a typical example of such a system. Previous studies have reported 13 ORs between Mg₂Sn and the matrix in this system. These studies explained and predicted these ORs using the preferential matching principle for primary planes. However, this traditional approach alone cannot fully explain why the number of observed ORs is considerably lower than the predicted number. This study systematically analyzes the previous experimental data to further explore the natural preference rules governing the primary planes. By applying lattice matching criteria that considers smaller mismatches and shorter matching vectors, several well-matched vector pairs are identified. However, no vector pair simultaneously exhibits the shortest length and minimal misfit. It is proposed that the presence of multiple well-matched vector pairs contributes to the coexistence of multiple ORs. A systematic analysis of the previous experimental results also reveals that preventing dislocations with long Burgers vectors is an important factor that further constrains the primary facets. A new analytical method focusing on the primary matching column—shared by primary and secondary facets—is introduced. The primary matching column must be parallel to the short Burgers vector of dislocations, unless it is aligned parallel to an invariant or near-invariant line. Based on the characteristics of the primary matching column, the observed ORs are classified, improving our understanding of ORs and explaining why most precipitates lie on the (0001)_α plane. These new findings provide insights into the coexistence of multiple ORs in other systems and contribute to a knowledge base for optimizing precipitate morphologies.