All-inorganic cesium lead bromide ( CsPbBr 3 ) perovskite quantum dots (QDs) with excellent optical properties have been regarded as good gain materials for amplified spontaneous emission (ASE). However, the poor stability as the results of the high sensitivity to heat and moisture limits their further applications. Here, we report a facile one-pot approach to synthesize CsPbBr 3 @ SiO 2 QDs at room temperature. Due to the effective defects passivation using SiO 2 , as-prepared CsPbBr 3 @ SiO 2 QDs present an enhanced photoluminescence quantum yield (PLQY) and chemical stability. The PLQY of CsPbBr 3 @ SiO 2 QDs reaches 71.6% which is higher than 46% in pure CsPbBr 3 QDs. The PL intensity of CsPbBr 3 @ SiO 2 QDs maintains 84% while remaining 24% in pure CsPbBr 3 after 80 min heating at 60°C. The ASE performance of the films is also studied under a two-photon-pumped laser. Compared with the films using pure CsPbBr 3 QDs, those with as-prepared CsPbBr 3 @ SiO 2 QDs exhibit a reduced threshold of ASE. The work suggests that room-temperature-synthesized SiO 2 -coated perovskites QDs are promising candidates for laser devices.