[en] It is a crucial factor for enhancing upconversion luminescence (UCL) by doping different metals under irradiation. In this article, a series of Na₃Gd(VO₄)₂:Ln³⁺ (NGVO:Ln³⁺) were prepared by sol-gel means with citrate and characterized using X-ray diffraction. Their UCL properties were systematically investigated. A wide multi-colour emission corresponding to different Ln³⁺ (Yb³⁺/Er³⁺/Tm³⁺/Ho³⁺) doping was obtained under single-wavelength excitation. It is worth pointing out that among all the studied samples, only the UCL intensity of NGVO:15%Yb³⁺/2%Er³⁺ was 1.74 times more than that of the sum under the excitation at 980 and 1550 nm due to the synergistic effect under simultaneous 980 and 1550 nm excitation. Interestingly, a higher S_a (5.54 x 10^-3 K^-1) for NGVO:15%Yb³⁺/2%Er³⁺ excited at 1550 nm could be obtained, which had an advantage over that at 980 nm excitation. The possible energy transfer mechanism of NGVO:15%Yb³⁺/2%Er³⁺ under single- and multi-wavelength excitation was also discussed in detail using an energy level diagram. To further improve the UCL intensity, NGVO:15%Yb³⁺/2%Er³⁺ doped with other rare-earth ions (La³⁺/Lu³⁺/Y³⁺) were synthesized, and their UCL intensity and Sa values were also improved to a certain extent. (author)