In this work,hexagonal phase NaY(Gd0.4)F4∶ Yb3+/Ho3+ nanocrystals were obtained by solvothermal method.The upconversion emission tuning from green to red in NaY(Gd0.4)F4∶ Yb3+/Ho3+ nanocrystals was successfully achieved by replacing Y3+ ions in the nanocrystal structure with Ce3+ ions under 980 nm excitation.The red upconversion emission intensity was enhanced with Ce3+ concentration increasing.The output colors for the samples can be clearly observed in a confocal microscopy setup.It was found that two efficient cross-relaxation between Ho3+ and Ce3+ ions had been employed to enhance red emission and suppress green emission.The possible upconversion mechanisms and conversion efficiency between Ho3+ and Ce3+ ions were investigated in detail.In addition,the influence of the matrix and surface properties on the upconversion emission of the samples were also discussed.