Luminescence thermometers are widely known to provide contactless and the high measurement accuracy. In this paper, the different levels of Er3+ concentration doped Ba0.60Sr0.40TiO3 (BST) powders are prepared by a sol-gel method and their structures and the temperature sensing characteristics have been studied. The temperature dependence of the upper quasi-conversion luminescence of Ba0.60Sr0.40TiO3 (BST): x% Er3+(x = 1, 2, 4, 6, 8) powders is systematically tested in the temperature range of 303 K–543 K under 980 nm excitation. Benefiting from the special energy levels of rare earth ions, for example, Er3+ shows different green emission intensity with increasing temperature due to a pair of thermally coupled energy levels 2H11/2 and 4S3/2. By measuring the fluorescence intensity ratio (FIR) of the green emission peak of Er3+ ion, the prepared sample can be used as a probe to measure the ambient temperature of the inserted Er3+ ion. With the increase of Er3+ concentration, the sensitivity of Ba0.60Sr0.40TiO3 (BST): x% Er3+(x = 1, 2, 4, 6, 8) powders first increases and then decreases, while the maximum sensitivity is obtained at 2% Er3+ concentration. In addition, the relative sensitivity and absolute sensitivity maxima are 0.42% K−1at 383 K and 1.54% K−1 at 303 K, respectively.