Lanthanum strontium ferrite (La 1−xSr xFeO 3, x = 0.1, 0.3, 0.5, 0.7) (LSF) films were prepared on platinized/silica/silicon (Pt/SiO 2/Si) substrates by a sol–gel method. The crystallization, surface morphology and dielectric properties of the LSF films have been studied. Among the samples, La 0.5Sr 0.5FeO 3 thin film have the most homogeneous, smooth surface and the best dielectric properties ( εr = 2881.58, tanδ = 1.20) at the frequency of 1 kHz. Mn-doping ( y) in La 0.5Sr 0.5FeO 3 further improves the dielectric properties ( εr = 2922.91, tanδ = 1.11) of the film. Both εr and tanδ values of the Mn-doped ( y = 0.02) La 0.5Sr 0.5FeO 3 films decreases with increasing the frequency. The biggest εr value is 3238.18 at the frequence of 0.02 kHz. [ABSTRACT FROM AUTHOR]