从考察按行程比系数Ｋ设计平面曲柄滑块机构的基本原理图入手，对最佳辅助角λ＊和最佳传动角（γｍｉｎ推）ｍａｘ的客观存在性给予了清晰、直观的几何解释，建立了求解最佳辅助角λ＊和最佳传动角（γｍｉｎ推）ｍａｘ的解析方法。据上，文章绘制出了简单通用、颇具工程设计实用价值的λ＊－Ｋ和（γｍｉｎ推）ｍａｘ－Ｋ两种线图。 Starting with the basic schematic diagram of designing a planar crank-slider mechanism according to the travel ratio K, a clear and intuitive geometric explanation is given for the objective existence of the optimal auxiliary angle λ * and the optimal transmission angle (γmin push) max, establishing To find the best auxiliary angle λ * and the best transmission angle (γmin push) max analytic method. According to the article, the article draws a simple and general, quite practical value of the engineering design λ * -K and (γmin push) max-K two kinds of line graph.