LiLuF4 host has been broadly used to incorporate rare earth activators for solid-state laser and bio-imaging applications. The particle shape can greatly influence the scattering and absorption of incident light, resulting in different radiatively transition properties of lanthanide activators. However, it remains a great challenge to largely tune the shape of tetragonal LiLuF4 particles. Herein, the LiLuF4:15Tb particles with different shapes, such as octahedral, distorted octahedral and sphere, were controlled synthesized by simply adjusting the lithium citrate content. The citric ion (Cit3−) was employed as a strong stabilizer and structural guide agent. The Cit3− content dependent shape evolution is also suitable for the LiYF4:15Tb system. The LiLuF4:15Tb particles involved film is verified to be suitable for high-resolution X-ray excited optical luminescence imaging. Our results give out a simple and novel route to tune the LiLuF4 particle shape, benefiting the study of shape-dependent optical properties of lanthanide doped LiLuF4 crystals.