There are many strategies to maintain the excellent photoluminescence (PL) characteristics of perovskite quantum dots (QDs). Here, we proposed a facile and effective method to prepare cyan CsPb(Cl/Br)₃/SiO₂ nanospheres at room temperature. Cubic CsPb(Cl/Br)₃ was obtained by adding a LiCl-H₂O solution and anion exchange reaction. With (3-aminopropyl)triethoxysilane as an auxiliary agent, a QDs/SiO₂ composite was extracted from a sol-gel solution by precipitate-encapsulation method. The transmission electron microscopy images and Fourier transform infrared spectra indicated the QDs were indeed embedded in silica substances. Besides, humidity stability and thermal stability show the composite possesses a great application value. Finally, cyan QDs@SiO₂ powder has a high PL quantum yield of up to 84%; the stable cyan fluorescent powder does have great potential to play a key role in commercial full spectrum display.