The Buddha Sutra of Impermanence is preserved in Khara-Khoto and the Canon Cave of Dunhuang. Khara-Khoto has preserved its texts both in Chinese script and Xixia script. The publications of Khara-Khoto literature preserved in Great Britain and Russia and that preserved in the Canon Cave of Dunhuang provide materials for a better understanding of its spread. This article researches and rearranges the residuals of the Buddhist canon in Xixia script preserved in the British Library [Or.12380-3700aRV(K.K.II.0258.m), Or.12380-3700b(K.K.II.0258.m) and Or.12380-3700bRV(K.K.II.0258.m)], and then makes a concise comparative study on different Buddha Sutra of Impermanence texts from Khara-Khoto and the Canon Cave of Dunhuang.