Ho 3+ /Yb 3+ co-doped and Ho 3+ /Yb 3+ /Li + tri-doped SrAl 2 O 4 ceramics were prepared by the conventional solid-state reaction and their up-conversion (UC) luminescence was characterized. Strong green emission (556nm) and weak red emission (664nm) were observed under the excitation of 980nm laser diode (LD) at room temperature. The up-conversion process is based on two-photon absorption. In Ho 3+ /Yb 3+ co-doped SrAl 2 O 4 ceramics, the UC intensity achieved its maximum as Yb 3+ concentration was 20mol% which was attributed to the energy transfer (ET) from Yb 3+ to Ho 3+ . Furthermore, the UC green luminescence intensity was largely enhanced by about six times in Li + doped SrAl 2 O 4 : Ho 3+ , Yb 3+ ceramics and the related mechanisms have been discussed.