A series of Li+ doped SrLu2O4∶Ho3+/Yb3+ phosphors are prepared with high-temperature solid-state reaction method. The Li+ doped samples maintain the primary orthorhombic structure. The Li+ ions can be introduced into the host lattice through the approach of substitutional doping and interstitial doping. By adding appropriate Li+ ions to the samples, the agglomeration of samples can be minimized and the average diameter of particles is about 3 μm. The impurities (OH- and CO32-) with high phonon energy can be reduced, which reduces the quenching centers and increases upconversion emission intensity. The intense green emission and weak red emission are observed under the excitation of the 980 nm laser, which are attributed to the 5F4, 5S2→5I8 and 5F5→5I8 transitions, respectively. With the introduction of Li+ ions to the SrLu2O4∶Ho3+/Yb3+ sample, the upconversion emission is found to be significantly enhanced, which is attributed to the modification of local crystal field symmetry around Ho3+ ions by Li+ doping. Compared with other alkali-metal-ion dopings, the Li+ doped sample has the strongest luminescence intensity due to the smallest ionic radius and the strongest electronegativity of Li+ ions. The analysis result of pump-power dependence show that the green and red emissions are both involved in a two-phonon process.