When a distant star，the sun and the observer are in a line，the Einstein’s ring can be viewed. Ignoring rotation of the sun，the gravitational field of solar system is described by Schwarzschild metric and then the null geodesic equation is solved exactly by elliptic integral.It must be apart from the sun at least 547.7 AU to observe the Einstein’s ring. However，the diameter of Einstein’s ring and the sun’s edge almost overlap each other so that it is very difficult to distinguish them under current technology.