Shuhoupin 書後品 (or Houshupin 後書品) is a critique of calligraphic art written by Li Sizhen 李嗣真 (?-696), who also wrote a (lost) book called Xu huapin lu 續畫品錄. The title was chosen to make the book a kind of supplement to Yu Jiuanwu's 庾肩吾 (487-551) Shupin 書品 from the Liang period 梁 (502-557).
It provides assessments of the artistic skills of 82 (81) painters from the early Han 漢 (206 BCE-220 CE) to the Tang period 唐 (618-907), and ranks them into 10 grades. Apart from the usual nine ranks (shangshang 上上, shangzhong 上中, shangxia 上下,...), Li adds the tenth, highest grade of "matchless" (yipin 逸品). He speaks of four masters who achieved this grade, but lists actually five persons, namely Li Si 李斯 (d. 208 BCE), Zhang Zhi 張芝 (d. 192 CE), Zhong Yao 鍾繇 (151-230), Wang Xizhi 王羲之 (303-361), and Wang Xianzhi 王獻之 (344-386; perhaps the "two Wangs" are counted as one person). He argues that the mastery of these particular calligraphers was very unique and without precedent, and could not be emulated by anyone else (qiong jue zhong gu, wu fu ji zuo 瓊絕終古,無復繼作).
Each ranking is justified in detail, and explains the strengths and weaknesses of calligraphers. The author adds brief biographies, and summarizes his judgment by laudatory appraisals (ping 評, zan 贊).
The text is included in the series Shuofu 說郛 (where the book is called Houshupin 後書品), and it it quoted in the Fashu yaolu 法書要錄, Shuyuan jinghua 書苑菁華 and Lidai shufa lunwen xuan 歷代書法論文選.