The present invention provides a phosphor powder with garnet-type structure and a light-emitting device prepared therewith. The phosphor powder has the chemical formula CaaLnb-kM1 cScdAleM2 fO12:Cek, wherein Ln represents a trivalent rare earth element, the trivalent rare earth element being at least one of Lu, Y and Gd; M1 represents at least one of Zr and Hf; M2 represents at least one of Ge and Si; 1.8 ≤ a ≤ 2.2; 0.78 ≤ b ≤ 1.2; 0.8 < c < 1.2; 0.8 < d < 1.2; 1.8 ≤ e < 2.2; 0.8 < f < 1.2; and 0 < k ≤ 0.15. An emission peak wavelength and a spectral coverage area of the phosphor powder can be adjusted by modifying the identity and ratio of the trivalent rare earth elements and by modifying the concentration of a luminescence center element Ce, thereby allowing the phosphor powder to meet practical requirements of different light-emitting devices with respect to the photochromic properties of light-emitting materials.