By reasonably designing and exploring the surface ligand of Quantum Dots（QDs）， this work adopts a one-step synthesis of perovskite QDs in the atmospheric environment. Utilizing 3-aminopropyl triethoxysilane as surface ligands， the core-shell structures of silica coated CsPbBr3 QDs （CsPbBr3@SiO2 QDs） were directly prepared by thermal injection method in the air. The effect of reaction time on the thickness of the silica shell was systematically studied， and the morphology and composition of core-shell QDs were characterized by transmission electron microscopy and X-ray photoelectron spectroscopy. The photoluminescence spectra were used to record the characteristics of light emission spectra under the environment of water， oxygen and lighting， and the time stability of spectra was analyzed and discussed. These results show that core-shell QDs with high-quality perovskite core and uniform silica shell were successfully prepared at a reaction time of 30 min. Benefitting from the coating of silica shell and organic supporting film， QDs optical film still maintained the high-efficiency photoluminescence， and its stability in water and oxygen environment had been greatly improved. The spectral peak and intensity of the optical film were even stable after 180 days. Furthermore， our core-shell perovskite QDs were applied in light emitting diode devices， showing bright light emissions with narrow full width at half maxima.