本文介绍绘制二元系各类相图的数学方法。它是把确定相图中分溶曲线的问题,转化为通过确定平面动力系统来确定初值的一条轨线的问题。这样,可以用计算机来绘制二元系的相图。同时也为从相图来研究二端元的活度和活度系数提供了一个新的途径。 This article introduces the mathematic method of drawing all kinds of phase diagram of binary system. It turns the problem of determining the dissolution curve in the phase diagram into a trajectory determining the initial value by determining the planar dynamical system. In this way, you can use the computer to draw the phase diagram of the binary system. It also provides a new way to study the activity and activity coefficients of two-terminal elements from the phase diagrams.