Ba0.65Sr0.35TiO3 (BST) nanopowders doped with Er3+ were prepared by sol-gel method. The absorption spectrum and photoluminescence (PL) spectrum of Er3+∶BST nanopowders was measured at room temperature. Based on the Judd-Ofelt theory, the intensity parameters of Er3+ in BST nanopowders were determined, Ω2=0.993×10-20 cm2, Ω4=1.665×10-20 cm2 and Ω6=0.540×10-20 cm2, and then the values of the line strengths, radiative transition probabilities and branching ratios of Er3+ were calculated. According to the PL spectrum, the emission bands centered at about 522, 545, 654 and 851 nm corresponding to 2H11/2→4I15/2, 4S3/2→4I15/2, 4F9/2→4I15/2, and 4S3/2→4I13/2 transition were observed, and the emission properties were also discussed. The results show that the Er3+∶BST nanomaterials are prospective candidates for applications in new photoelectric devices