CsPbX3 (XCl, Br, I) perovskite quantum dots (PeQDs) have excellent properties, which makes it the most promising optoelectronic materials for the next generation of light-emitting diodes (LEDs) and display devices fields. However, CsPbX3 PeQDs have poor-term stability and easily decompose in moist or heat conditions. In this paper, the KaCs1−aPbBr3 @SBA-15 composite was prepared at room temperature. Alkali metal ion doping can enhance the luminous intensity and tune the emission spectrum of CsPbBr3 PeQDs, while the introduction of the SBA-15 matrix improves the stability of the KaCs1−aPbBr3 PeQDs (a=0, 0.1, 0.25, 0.35, 0.4, 0.45). When the molar ratio of K+/Cs+ is 0.4 / 0.6, the PL intensity of CsPbBr3 PeQDs increased by 21.4%. The luminous intensity of K0.4Cs0.6PbBr3 @SBA-15 composite is further increased by 18.8% compared to the K0.4Cs0.6PbBr3 PeQDs, and its moisture and heat resistance are significantly improved. The PL intensity of K0.4Cs0 6PbBr3 @SBA-15 can maintain 52% of the initial brightness after immersion in deionized water for 21 days, as well as reaching 95% of the initial value in the heating/cooling cycle treatment. Such excellent properties make the KaCs1−aPbBr3 @SBA-15 composite an ideal material for lighting and display applications.