Halide perovskite quantum dots (QDs) have been considered to be an outstanding optoelectronic material. However, their poor stability caused by their large specific surface area and high sensitivity to moisture, greatly hinders their practical application. Here, a simple silica (SiO₂)-coating process is adopted to solve this problem without affecting their optical properties. Firstly, monodispersed CsPbX₃ (X = Cl, Br, I) with cubic morphologies (~8 nm edge lengths) are successfully obtained using a modified hot-injection method, omitting the links of drying and degassing which can reduce energy consumption and save cost. Next, CsPbX₃@SiO₂ nanoparticles with spherical morphologies (1.2 μm) are obtained through a novel method based on the high hydrolytic rate of tetramethyl orthosilicate (TMOS) using CsPbX₃ as the precursor. Photostability tests indicate that the CsPbBr₃@SiO₂ QDs are markedly more stable than the pure CsPbBr₃. The PL intensity of the CsPbBr₃@SiO₂ dispersed in a mixed solution of toluene and water retained 77% of the initial value even after 12 h, which was much higher than the pure CsPbBr₃. Similar experimental results are also observed when CsPbBr₃@SiO₂ and CsPbBr₃ were dispersed in toluene exposed to air. This material provides a novel platform for the application of perovskite quantum dots in light-emitting device applications.