e astronomical systems was basically the evolution of the computation of <i>Sh&#224;ngyu&#225;n</i>." This article briefly introduces the concept of <i>Sh&#224;ngyu&#225;n</i>, its origin, its computation, how the <i>Sh&#224;ngyu&#225;n</i> system was used to adjust the astronomical constants, and the abolishment of the system. The information is taken from the books <i>Chinese Astronomical Systems and Mathematics</i><sup><a href="Shangyuan.html#Qu2005a">[1]</a></sup> and <i>Chinese Mathematical Astronomy</