Abstract: The stress-deformation behaviour of a blast-fill dam at different stages was examined based on in-situ monitoring data and finite element analysis (FEA). The mechanical behaviour and the impervious structures of blasting rockfill were investigated. Comparative analysis showed that the maximum settlement of the blasting rock occurred at the top of the blasting rockfill. Different from the conventional dam, the maximum settlement is located at 2/3 of the dam. The compressibility of the blasting rockfills and the slope deposit were the main factor for their large settlement. The numerical simulation was used to analyse the influence of stress-deformation behaviour of impervious structures. The results showed that due to the complex composition of the dam material and the large difference in the mechanical properties of the material, some uneven settlement of the dam occurred locally. Large deformation and stress occurred at the reverse arc below the 700.00 m platform, which was a greater impact on the deformation of the asphalt concrete wall. The rise of the water level caused a great change in the stress-deformation behaviour of the asphalt concrete wall, and the stress-deformation of the impermeable body increased significantly. The above summary is a comprehensive and true reflection of the operational behaviour of the blasting rockfill body, dam body and impervious structures of the blast-fill dam. The findings of this study are of great value for the study of the safety state of high face rock-fill dam, soft rock dam, slag field, landslide and quake lake.