<p>Biomass burning (BB) is a significant source for dicarboxylic acids (diacids) and related compounds that play important roles in atmospheric chemistry and climate change. In this study, a combustion chamber and oxidation flow reactor were used to generate fresh and aged aerosols from burned rice, maize, and wheat straw to investigate atmospheric aging and the stable carbon isotopic (δ<sup>13</sup>C) composition of these emissions. Succinic acid (C<sub>4</sub>) was the most abundant species in fresh samples; while, oxalic acid (C<sub>2</sub>) became dominant after atmospheric aging. Of all diacids, C<sub>2</sub> had the highest aged to fresh emission ratios of 50.8 to 64.5, suggesting that C<sub>2</sub> is largely produced through secondary photochemical processes. Compared with fresh samples, the emission factors of ketocarboxylic acids and α-dicarbonyls increased after 2-day but decreased after 7-day aging, indicating short residence time and further atmospheric degradation from 2- to 7-days. The C<sub>2</sub> δ<sup>13</sup>C values for aged biomass samples were higher than those of urban aerosols but lower than marine or mountain aerosols, and the C<sub>2</sub> δ<sup>13</sup>C became isotopically heavier during aging. Relationships between the reduction in volatile organic compounds (VOCs), such as toluene, benzene, and isoprene, and increase in dicarboxylic acids after 2-day aging indicate that these volatile organic compounds led to the formation of dicarboxylic acids.</p>