Efficiently up-conversion luminescence can be achieved by replacing the traditional sensitizer Yb3+ ions with Er3+ ions in LaVO4 host under 1550nm excitation. In contrast to other up-conversion luminescence materials, such as Y2O2S:Er3+, Y2O3:Er3+, YOCl:Er3+, which exhibit red emission, LaVO4:Er3+ samples present an abnormal green emission under 1550nm excitation. Excited state absorption is the dominating up-conversion luminescence mechanism at low doping concentrations of Er3+, whereas energy transfer up-conversion predominates at high concentrations of Er3+. Infrared thermal imaging is adopted to investigate the thermal effects of LaVO4:Er3+ sample under 1550nm irradiation. It shows a rapid heating process within 1∼5s and LaVO4:0.21Er3+ sample yields a temperature rising of ΔT=66.46°C under 1550nm irradiation (207mW) within 60s. Therefore, the temperature sensor based on up-conversion luminescence of Er3+ ions 2H11/2/4S3/2 thermally coupled levels produced significant measurement errors at low temperatures because of the thermal effects and non-uniform temperature of the incident light spot area.