Bi4−xHoxTi3O12 (BHT-x) thin films with Ho content x=0.2, 0.4, 0.6, 0.8, and 1.0 were prepared on Pt/Ti/SiO2/Si substrates by a sol–gel method. Effects of Ho contents on the microstructure and ferroelectric properties of BHT-x thin films were investigated. All the BHT-x samples consist of the Bi-layered Aurivillius phase. The lattice constants along the a, b, and c axes decrease with the increase of x. The remanent polarization (2Pr) and dielectric constant (ɛr) increase firstly and then decreases with the increase of the Ho content, while the leakage current density shows opposite trend. BHT-0.4 film exhibits the best electrical properties with 2Pr 44.2 μC/cm2, 2Ec 323.7 kV/cm, ɛr 489 (at 1 MHz), dielectric loss 0.018 (at 1 MHz), leakage current density 8.0 × 10−8 A/cm2 (under 200 kV/cm), as well as the strongest fatigue resistance (the polarization loss is only 3% after 4.46 × 109 switching cycles).