This paper expounded and proved some special geometric relations of the planar crank - rocker mechanisms , gave a new graphic method for designing the planar crank - rocker mechanisms 摘要根據(jù)平面曲柄搖桿機構(gòu)的一些特殊幾何關(guān)系,給出了設(shè)計平面曲柄搖桿機構(gòu)的新圖解法。