本文介绍一种输入、输出轴线同轴的凸轮链条步进机构。研究了该种步进机构的零阶至二阶传动函数；提出了从动链轮在其步进角的中间范围内，作恒速比传动的几何条件以及实现给定步进角的机构尺寸的设计方法。设计实例表明了该种步进机构的设计与制造均较简单，传动平稳 This article describes a coaxial input and output cam chain stepper mechanism. The zero-order to second-order transmission functions of this type of step mechanism are studied. The geometric conditions of the driven sprocket for constant speed ratio transmission in the middle of its step angle and the size of the mechanism for realizing the given step angle Design method. The design example shows that the design and manufacture of this kind of stepping mechanism are relatively simple and the transmission is stable