全球定位系统( GPS) 对时钟的精度提出了很高的要求. 由于GPS 卫星的速度和高度，本文从狭义相对论和广义相 对论两方面论述了无论是运动时钟变慢，还是引力场中高处时钟加快的效应都将对GPS 系统时钟的精度产生不可忽视的影响.这是大学物理课程讲述相对论的一个极好的例子.

Global positioning system ( GPS) on the accuracy of the clock makes a very high demand. Since the speed and the altitude of the satellite，this paper shows that both effects from the special relativity which make motion clock slow and from the general theory of relativity which makes the clock at higher place in a gravitational field fast be large enough，thus the influence of relativity to accuracy of satellite clocks can not be ignored. This is a very good example when we talk about the application of relativity in college physics course.