Abstract: Objective: To analyze the differences of chemical composition of Pericarpium Citri Reticulatae 'Chachi' under different aging years, and to provide the theoretical and scientific basis for the aging mechanism of Pericarpium Citri Reticulatae 'Chachi'. Methods: UPLC-MS/MS widely-targeted metabolomics technology was used to detect and analyze the chemical constituents of three kinds of Pericarpium Citri Reticulatae 'Chachi' aged seven years, nine years and eleven years. PCA and OPLS-DA statistical analysis methods were used to identify differential metabolites. Results: A total of 778 compounds of 27 categories were identified. Main components were flavonoids (121) and terpenoids (90). According to the VIP value greater than 1 and the P-value less than 0.05, 121 differential metabolites were screened, 65 differential metabolites of 22 categories between the 11-year aging group and 9-year aging group, 62 differential metabolites of 20 categories between the 11-year aging group and 7-year aging group, 32 differential metabolites of 14 categories between the 9-year aging group and 7-year aging group. The numbers and types of differential metabolites in Pericarpium Citri Reticulatae 'Chachi' tended to increase after aging for 7~11 years. There were differences in metabolites of Pericarpium Citri Reticulatae 'Chachi' under different aging years. With the increase of aging time, the aging time had great influence on flavonoids, terpenoids, amino acid and derivatives. The key pathways with the highest correlation with differential metabolites were: Monoterpenoid biosynthesis, flavone and flavonol biosynthesis, the metabolic pathways involved in amino acid and derivatives (alanine, aspartate and glutamate metabolism, glycine, serine and threonine metabolism, cysteine and methionine metabolism). Conclusion: Widely-targeted metabolomics technology can be used to identify and analyze the chemical components of Pericarpium Citri Reticulatae 'Chachi' with high efficiency. It has established important technical foundation for researching the aging mechanism of Pericarpium Citri Reticulatae 'Chachi'.