Mulberry-shaped tin oxide (SnO₂) hierarchical architectures and samarium oxide (Sm₂O₃) loaded tin oxide with different amounts (0.5, 1, 2.5, and 4 mol% Sm₂O₃) were successfully synthesized by facile hydrothermal synthesis method and simple isometric impregnation method. The gas sensing performance of the sensors based on pure SnO2 and Sm2O3 loaded SnO₂materials were systematically investigated. The results indicated that Sm₂O₃loading considerably affected the improvement of the sensing performance of the SnO₂sensor. The 2.5 mol% Sm₂O₃/SnO₂exhibited the highest response (41.14) to 100 ppm acetone, the response was 2.29 times higher than that of pure SnO₂(18). In addition, with 2.5 mol% Sm₂O₃loading, the low detection threshold of the sensor dropped from 500 ppb to 100 ppb. The enhanced gas sensing performance was mainly bacause of the increased oxygen vacancies created by the substitution of samarium in the SnO₂lattice, which enhanced the adsorption of oxygen and the exceptional catalytic effect of Sm₂O₃.