分析了含有一个移动副平面四连杆机构产生对称连杆曲线的条件、曲线类型和变化规律对其中几种主要曲线的应用进行了讨论，通过实例说明了相应机构的综合过程 The condition, curve type and variation of the symmetrical connecting rod curve with a four - link mechanism with moving secondary plane are analyzed. The application of several main curves is discussed. The synthesis process of the corresponding mechanism is illustrated by examples.