To study the application of precise powder decoction pieces (PPDP) of Cinnamonum cassia Presl (CCP) with chemical fingerprint chromatography and DNA molecular identification technology were used on quality system. Methods: PsbA-trnH sequence was used as DNA barcode to indentify CCP. Different specifications of PPDP were prepared, and their dry extract content rates were compared with that of original slices. HPLC fingerprint of CCP was established and the contents of cinnamic acid and cinnamic aldehyde were measured. Common peak of fingerprint was demarcated. The common peak relative peak areas and similarity evaluation of each sample were compared. Results: CCP could be accurately identified by psbA-trnH sequences. The extract rate of the concentration of cinnamic acid and cinnamic aldehyde of PPDP were slightly higher than that of the original pieces, and the content differences decreased significantly. RSD of inter-assay dissolution of cinnamic acid and cinnamic aldehyde of the original slices were 5.19% and 26.80%, respectively, which could be reduced to 0.36% and 0.42% after mixing and preparing into PPDP. The relative peak areas of the 10 common peaks were increased, and uniformity was significantly improved. Conclusion: The precise powder decoction pieces of CCP can improve the extraction efficiency and uniformity of original slices.