Integrating germanium (Ge) thin film on silicon-on-insulator (SOI) substrate and fabricating Ge fin field-effect transistors (FinFETs) are demonstrated in this paper. Directly grown Ge film on a high-resistivity thin SOI substrate provides a good platform for fabricating advanced Ge devices. The SOI structure could effectively suppress junction leakage; therefore, high I ONIOFF ratio (∼5× 105, at VD=0.1V) of the drain current is achieved. Tri-gate structure provides better short-channel control abilities for the Ge FinFETs, and the drain-induced barrier lowering and threshold voltage (VTH) shift can be maintained at the level of ∼ 110 mVV and ∼ 0.1 V, respectively, for Ge n-channel FinFET with Lchannel=120nm and WFin=40nm. Multifin Ge FinFET with Lchannel=170nm and WFin=50 nm is also illustrated. Both N-and P-FinFETs possess high IONIOFF ratio over 10 4. Besides, the subthreshold swing could be reduced around 25% after forming gas annealing.