Uniform Pr2Sn2O7 nanospheres were synthesized via a simple solvothermal route with ethylenediamine as the solvent. The as-prepared Pr2Sn2O7 nanospheres with the diameters of 20-50 nm are composed of nanoparticles with a size of 3-5 nm. The introduction of water into the reaction solution results in the formation of smaller Pr2Sn2O7 nanospheres with poor crystallinity or SnO2 particles, indicating that ethylenediamine has a complicated effect on the generation of Pr2Sn2O7 nanospheres. The UV-vis spectrum reveals that the band gap of synthesized Pr2Sn2O7 nanospheres is about 4.19 eV, much higher than the theoretical value calculated by DFT. The enhanced gas sensing performances could be attributed to the unique mesoporous nanosphere structure, which can significantly facilitate gas diffusion and mass transportation in sensing materials.