Rare-earth stannate(Ln_2Sn_2O_7(Ln = Y, La–Lu)) nanocrystals with an average diameter of 50 nm were prepared through a facile microwave hydrothermal method at 200°C within 60 min. The products were well characterized. The effect of reaction parameters such as temperature, reaction time, p H value, and alkali source on the preparation was investigated. The results revealed that the p H value plays an important role in the formation process of gadolinium stannate(Gd_2Sn_2O_7) nanoparticles. By contrast, the alkali source had no effect on the phase composition or morphology of the final product. Uniform and sphere-like nanoparticles with an average size of approximately 50 nm were obtained at the p H value of 11.5. A possible formation mechanism was briefly proposed. Gd_2Sn_2O_7:Eu~(3+) nanoparticles displayed strong orange-red emission. Magnetic measurements revealed that Gd_2Sn_2O_7 nanoparticles were paramagnetic. The other rare-earth stannate Ln_2Sn_2O_7(Ln = Y, La–Lu) nanocrystals were prepared by similar approaches. Rare-earth stannate (Ln = Y, La-Lu)) nanocrystals with an average diameter of 50 nm were prepared through a facile microwave hydrothermal method at 200 ° C within 60 min. The products were well characterized. The effect of reaction parameters such as temperature, reaction time, p H value, and alkali source on the preparation was investigated. The results revealed that the p H value plays an important role in the formation process of gadolinium stannate (Gd_2Sn 2 O 7) nanoparticles. source had no effect on the phase composition or morphology of the final product. Uniform and sphere-like nanoparticles with an average size of approximately 50 nm were obtained at the p H value of 11.5. A possible formation mechanism was briefly proposed. Gd_2Sn_2O_7: Eu ~ (3+) displayed strong orange-red emission. Magnetic measurements revealed that Gd_2Sn_2O_7 nanoparticles were paramagnetic. The other rare-earth stannate Ln_2Sn_2O_7 (Ln = Y, La-Lu) nanocrysta ls were prepared by similar similar.