Based on a hydrothermal method, the Ce3+/Tb3+ co-doped Ba Gd F5 nanocrystals were synthesized by controlling the introduction concentration of Ba2+ and Gd3+. The samples were characterized by X-ray diffraction(XRD), field emission scanning electron microscopy(FESEM) images, photoluminescence(PL) excitation, and emission spectra, as well as the photoluminescence dynamic decay curves. With the increase of the Ba2+ concentration in the synthesis procedure, the positions of diffraction peaks of XRD patterns move toward lower degree, and the case of the samples synthesized with the increase of the Gd3+ concentration is contrary, which consists well with each other. The FE-SEM images suggest that the BaGdF5 nanocrystals are in spherical morphology,and the average diameters decrease with the increase of Ba2+ or Gd3+ concentration. For the 4f–5d transition of Ce3+ is sensitive to the environment of local lattice, the PL excitation and emission spectra of the samples are different. The 4f–4f transition of Tb3+ also presents different optical properties in different host lattices. The variations of the optical properties of Ce3+ and Tb3+ as well as the lifetime of the 5D4+7F5 emission of Tb3+ are also consistent well with each other in the two series of samples. Based on a hydrothermal method, the Ce3 + / Tb3 + co-doped Ba Gd F5 nanocrystals were synthesized by controlling the introduction of Ba2 + and Gd3 +. The samples were characterized by X-ray diffraction (XRD) images, photoluminescence (PL) excitation, and emission spectra, as well as the photoluminescence dynamic decay curves. with the increase of the Ba2 + concentration in the synthesis procedure, the positions of diffraction peaks of XRD patterns move toward lower degree, and the case of the samples synthesized with the increase of the Gd3 + concentration are contrary, which consist well with each other. The FE-SEM images suggest that the BaGdF5 nanocrystals are in spherical morphology, and the average diameters decrease with the increase of Ba2 + or Gd3 + concentration. For the 4f-5d transition of Ce3 + is sensitive to the environment of local lattice, the PL excitation and emission spectra of the samples are different. The 4f-4 f transition of Tb3 + also presents different optical properties in different host lattices. The variations of the optical properties of Ce3 + and Tb3 + as well as the lifetime of the 5D4 + 7F5 emission of Tb3 + are also consistent well with each other in the two series of samples .