Shiyaolun 世要論 "Treatise on important matters on earth" is a political treatise written by the Cao-Wei-period 曹魏 (220-265) scholar Huan Fan 桓範 (d. 249 CE). Huan Fan was Chamberlain for the National Treasury (dasinong 大司農) and was killed by the general and regent Sima Yi 司馬懿 (179-251).
A book with the title of Zhengyaolun 政要論 "Treatise on important matters in politics" with a length of 12 juan is listed in the imperial bibliography Jingji zhi 經籍志 of the official dynastic history Suishu 隋書, among the legalist treatises. The bibliographical chapter in the Jiutangshu 舊唐書 calls it Daiyaolun 代要論 in order to avoid the tabooed personal name of Emperor Taizong 唐太宗 (r. 626-649), Li Shimin 李世民.
There are many different titles for this book to be found in writings quoting from it, like Shiyaolun, Huan Fan xinshu 桓範新書 "New books by Huan Fan", Huan Fan shilun 桓範世論 "Huan Fan's treatise on the generations", Huangong shilun 桓公世論 "Sir Huan's treatise for the generations",
The book was lost, yet the Qing-period 清 (1644-1911) scholar Ma Guohan 馬國翰 (1794-1857) reconstructed it as far as possible from quotations in Tang-period 唐 (618-907) encyclopaedias like Beitang shuchao 北堂書鈔, Chuxueji 初學記 and Yiwen leiju 藝文類聚, the commentary on the anthology Wenxuan 文選, or the Song-period encyclopaedia Taiping yulan 太平御覽.