本文通过研究单摆实验时发现单摆运动与对应的圆周运动周期相同,经细致的计算发现,单摆过程中任意一点都与圆周运动的相应点相关联,单摆的周期就是圆周运动的周期,周期公式变得简单易懂.进而将简谐运动与圆周运动相关联,指出两者的对应关系,推导出简谐运动的周期公式.读罢本文,可使人感觉到深奥的公式并非遥不可及,对科学探究的兴趣也会进一步增强. In this paper, by studying the single pendulum experiment, we find that the single pendulum motion is the same as the corresponding circular motion cycle. After detailed calculation, it is found that any point in the pendulum process is related to the corresponding point of the circular motion, and the period of the single pendulum is the cycle of the circular motion. The periodic formula becomes simple and easy to understand. Furthermore, the harmonic motion is associated with the circular motion, indicating the corresponding relationship between the two, and deducing the periodic formula of the harmonic motion. After reading this article, people can feel that the deep formula is not distant. Unable to follow, interest in scientific inquiry will be further enhanced.