$Sr_xBi_{2.4}Ta_2O_9$ (SBT) thin films of 150 nm thickness were prepared using LSMCD (Liquid Source Misted Chemical Deposition) process with variation of the Sr/Ta mole ratio of 0.35~0.65, and their crystalline phase, microstructure, ferroelectric properties and leakage current characteristics were investigated. Ferroelectric characteristics of the LSMCD-derived SBT films were optimized at the Sr/Ta moleratio of 0.425. The remanent polarization (2Pr) and coercive field (Ec) of the SBT film with the Sr/Ta mole ratio of 0.425 were measured as 15.01 $mu$C/$ extrm{cm}^2$ and 41 kV/cm at an applied voltage of $pm$5 V respectively. LSMCD-derived SBT films with the Sr/Ta mole ratio of 0.35~0.5 exhibited leakage current densities lower than $10^{-5} A/ extrm{cm}^2$ at an applied field of 100 kV/cm, and excellent fatigue-free characteristics of the remanent polarization decrement less than 1% after $10^{10}$ switching cycles at$pm$5 V.