The Rec.2020 blue light-emitting standard requires the center wavelength is (465 ± 3) nm, and the full width at half maxima (FWHM) is less than 20 nm, and the color gamut coordinate is (0.131, 0.046). To benchmark the standard, the performance of all inorganic perovskite quantum dots was investigated. The various blue light-emitting series were synthesized via the methods of adjusting halogen ratio, ion-exchange, and adjusting the number of octahedral layers, respectively. Their performances for Rec. 2020 blue light-emitting standard were discussed comprehensively. The results indicate that the CsPbCl_1.5Br_1.5 obtained by adjusting the halogen ratio has the best performance in terms of light-emitting wavelength, monochromaticity, luminescence efficiency, etc., with a center wavelength of 463.9 nm, an FWHM of 18.6 nm, and a color gamut coordinate of (0.137, 0.041). This work lays a foundation for the further development of high-definition blue light emitting devices and display systems based on all-inorganic perovskite systems.