Sputter deposition simulations and subsequent mechanical testing, including indentation and uniaxial tension, simulations were conducted to study the mechanical behavior of polycrystalline aluminum thin films with nano-scale columnar grains on Ti substrate. The molecular dynamics (MD) simulations for deposition and indentation adopted the interatomic potential of a tight-binding, many-body type among the aluminum atoms. To include the ionion interactions, the pair-wise Moliere potential was adopted to model the interaction between working gas and deposited atoms during deposition. The as-deposited films did not show clear grain boundaries, but after thermal annealing, grains grow and form nanocrystalline structure with a grain size of 8 nm. Indentation results show little pileups around indents. Upon loading, dislocation density increases, and dislocations are emitted from the indenter tip. However, the high dislocation density state relaxes with time in the constant load segment. MD simulations for uniaxial tensile tests adopted the embedded atom method (EAM) for interatomic potential. It is found that by increasing the strain rate 1000 times, the yield stress is doubled in the extremely high strain rate limit. Dislocation mobility and dislocation generation are two distinct mechanisms in the plastic behavior of the nanoscale sample under the high strain rates.