Chinese Buddhist apocryphal scriptures， due to the reason that they were not told by the Buddha himself， have been forbidden by ″orthodox″ Buddhism. Except a small portion that survives， most of them have been lost. Among the Dunhuang documents discovered at the beginning of the last century， more than one hundred Buddhist apocryphal scriptures are preserved， most of which are not included in the Buddhist canons published before the Qing dynasty， and therefore become valuable primary sources for the study of the sinicization of Buddhism. The majority of the Buddhist apocryphal manuscripts preserved in Dunhuang corpus are fragments. Some of the fragments were from the same scroll that was torn into pieces， which seriously impedes relevant research. In this sense， the reconstruction of the Dunhuang fragmentary manuscripts is one of the fundamental tasks for the collation and study of Dunhuang documents．Zhaifa Qingjing Jing (the Scripture on the Purification of the Fast Discipline), Fawang Jing(the Scripture on the King of the Dharma) and Shiwang Jing(the Scripture on the Ten Kings) are three Buddhist apocryphal scriptures that were popular during the Sui dynasty, the Tang dynasty, the Five Dynasties and the early Song dynasty. After a thorough study of the three scriptures in the Dunhuang corpus, this article gives a definite number and the completeness of their extant manuscripts . Based on the comparative analysis of the content connectedness, the fragmentary characters, the same formats, the same handwritings, we pieced 32 fragments of the three apocryphal scriptures together into 10 groups. Among them, there are 12 manuscripts of Zhaifa Qingjing Jing, and 2 of them are pieced together into 1 group, which isДх10418+Дх10304. There are 24 manuscripts of Fawang Jing, and 15 of them are pieced together into 5 groups, which are BD630+S.9791, Дх3968+Дх5387+Дх3989, Дх6546+Дх6140+Дх1109+Дх5080+Дх6080, S.8438+S.12368+S.7269, and Дх9438 +Дх5513. There are 50 manuscripts of Shiwang Jing, and in addition to the manuscripts pieced together by previous scholars, 15 of them are pieced together into 4 groups, which are S.2489+S.10154, BD8066+S.4530, Дх3906+Дх3862+Дх501 and Дх6612B…Дх7919+Дх7960+Дх6612A+Дх6611B+Дх7909…Дх8062+Дх6611A. The reconstruction work has patched up the scattered fragments, and some of them now make up complete scrolls with complete beginnings and ends, such as the 7th group (S.2489+S.10154) and the 8th group (BD8066+S.4530), etc. Based on the more complete information provided by the reconstructed manuscripts, it is possible to correctly name these fragments. For instance, the two fragments Дх3862 and Дх501 in the 9th group, which were formerly identified as ″A Template of Yuanwen (Literature of Hope)″ and ″Buddhist Sūtra″ respectively, can now be pieced together with the fragment Дх3906 and re-identified as Yanluowang Shouji Jing (the Scripture on the Vyākarana of the Yamarāja) according to the title at the beginning of the reconstructed manuscript. This has also made it possible to correct the previous errors and the misidentifications of the recto and verso of the manuscripts. For example, two sets of fragments, Дх7909+Дх7919+Дх7960+Дх8062 and Дх6611+Дх6612R-V in the 10th group were wrongly patched and misidentified in Dunhuang Manuscripts in Russian Collections. The patching-up shows that the two fragments Дх6611 and Дх6612 are not the recto and verso of the manuscript, but the upper and lower parts of the same side. Therefore, the patching-up of the Dunhuang fragmentary manuscripts contributes to a better knowledge of these manuscripts and more objective, reliable judgments of their formats, contents and characteristics.