【Objective】 Purple soil is weak in erosion resistance, and its soil aggregates are also vulnerable in structure. This study was oriented to explore how to reasonably utilize organic material resources, like crop straw, and improve structure of the purple soil, and how organic carbon is distributed in soil aggregates of the purple soil in the Sichuan Basin. 【Method】A tract of farmland under the rape/maize rotation ecosystem was selected for an in-situ filed experiment to explore effects of application of chemical fertilizer coupled with biochar and/or crop straw on content and stability of soil aggregates and soil organic carbon of the purple soil and distribution of organic carbon in aggregates by fraction. The experiment was designed to have control (CK) and 5 treatments, that is, CK (application of chemical fertilizer only), BC (application of chemical fertilizer + 8 000 kg•hm^-2biochar), CS (application of chemical fertilizer + 8 000 kg•hm^-2straw), 0.5BC (application of chemical fertilizer + 4 000 kg•hm^-2 biochar), 0.5CS (application of chemical fertilizer + 4 000 kg•hm^-2 straw) and BC+CS (application of chemical fertilizer + 4 000 kg•hm^-2biochar and 4 000 kg•hm^-2 straw). 【Result】Results show: (1)compared with the control (CK), all the treatments, except for Treatment 0.5BC, increased the content of >2 mm aggregates, while reducing the content of <0.053 mm aggregates. They also increased mean weight diameter (MWD) and geometric mean diameter (GMD) of the water-stable soil aggregates and content of the >0.25 mm aggregates (R0.25), with Treatment CS, in particular, where the effects became more significant with rising straw application rate. Treatment CS+BC significantly increased the content of 0.25~2 mm water-stable aggregates. (2)Except for Treatment CS, all the treatments significantly increased the content of total soil organic carbon as compared with CK. Among them, Treatment BC and CS+BC treatment did by 45.55% and by 44.45%, respectively (P<0.05), and the effect of Treatment CS was not so significant. With rising biochar application rate, the content of total organic carbon in the soil increased correspondingly. The increase was especially significant in <0.053 mm and >2 mm fractions of soil aggregates; Compared with other treatments, Treatment BC increased the content of organic carbon in all soil aggregates in the soil, regardless of size fraction, and followed by Treatment CS+BC in this effect. (3)By calculating contribution rate of each fraction of aggregates to total organic carbon in the soil, it was found out that the effects of the treatments increasing contribution of soil aggregates to total organic carbon in the soil were the most significantly reflected in the 0.25~2 mm and <0.053 mm fractions of soil aggregates. However, Treatment CS was the only one that significantly increased the organic carbon contribution rate of the >2 mm fraction of soil aggregates, or by 53.53% as compared with CK, and Treatment CS+BC and 0.5BC increased the rate of the <0.053 mm fraction of aggregates by 26.20% and 48.63%, respectively. (4)Application of straw and/or biochar increased the biomass and economic yield of maize and rapeseed, especially Treatments CS, BC, and CS+BC in the experiment. 【Conclusion】Combined application of straw and/or biochar with chemical fertilizer is an effective practice to improve structure of and increase carbon content in the purple soil.