易辛模型(Ising model，(英语发音：/ˈaɪsɪŋ/; 德语：[ˈiːzɪŋ])，是一个以物理学家恩斯特·易辛为名的数学模型，用于描述物质的铁磁性。该模型中包含了可以用来描述单个原子磁矩的参数 ，其值只能为+1或-1，分别代表自旋向上或向下，这些磁矩通常会按照某种规则排列，形成晶格，并且在模型中会引入特定交互作用的参数，使得相邻的自旋互相影响。虽然该模型相对于物理现实是一个相当简化的模型，但它却和铁磁性物质一样会产生相变。事实上，一个二维的方晶格易辛模型是已知最简单而会产生相变的物理系统。

The Ising model (/ˈaɪsɪŋ/; German:[ˈiːzɪŋ]), named after the physicist Ernst Ising, is a mathematical model of ferromagnetism in statistical mechanics. The model consists of discrete variables that represent magnetic dipole moments of atomic spins that can be in one of two states (+1 or −1). The spins are arranged in a graph, usually a lattice, allowing each spin to interact with its neighbors. The model allows the identification of phase transitions, as a simplified model of reality. The two-dimensional square-lattice Ising model is one of the simplest statistical models to show a phase transition.