The effects of biochar application on soil aggregates under different sieving methods were studied experimentally to provide a theoretical basis for the agricultural utilization of biochar. Four levels of biochar dosage (0, 10, 20 and 30 t/hm²) and two levels of nitrogen fertilizer dosage (0 and 150 kg/hm²) were set up in the experiment. Through two-year field positioning test, the distribution and stability of soil aggregates in 0—30 cm soil layer were measured and analyzed by dry sieving method and wet sieving method. The results showed that under the two sieving methods, the distribution trends of soil aggregates of each particle size in different treatments were basically the same. The mechanical soil aggregates obtained by the dry sieving method were mainly of ＞5 mm, 2~5 mm and 0.5~1 mm, while the water-stable aggregates obtained by the wet sieving method were mainly of 0.25~0.5 mm and ＜0.25 mm. The mean weight diameter (MWD) and geometric mean diameter (GMD) of soil aggregates in the dry sieving method were higher than those in the wet sieving method. In all treatments under wet sieving method, whether nitrogen was applied or not, both MWD and GMD increased with the increasing of biochar content. Among them, the MWD and GMD of the B0N0 treatment were the smallest, and the diameter of the soil aggregates in B3N0 (single application of biochar) was the largest, which was significantly higher than that of B0N0 by 60% (MWD) and 52% (GMD), respectively. The soil aggregate destruction rate (PAD) decreased with the increasing of biochar amount, while the soil aggregate stability rate (WASR) increased with the increasing of biochar amount. The fractal dimension (D) of each treatment in the dry sieving method was lower than that in the wet sieving method. The D value decreased continuously with the increasing of the biochar amount, and the fractal dimension of B3 biochar was the lowest, which were 2.63 (B3N0) and 2.64 (B3N1), respectively, 3.3% and 2.9% lower than that of the control. There was a significant negative correlation between the fractal dimension (D) and the content of soil aggregate larger than 0.25 mm (R_＞0.25). Under the experimental conditions, the soil aggregate stability was the best when the amount of biochar was 30 t/hm². At the same time, the wet sieving method could better simulate the field environment than the dry sieving method, and truly reflect the distribution and stability of soil aggregates.