Based on a field test on a purposely-built loose fill slope, a two-dimensional finite element model is established for coupled hydro-mechanical analyses of slope performance under controlled infiltration conditions. This paper presents a series of parametric study for investigation into the effect of wetting by surface and sub-surface infiltration on the initiation and growth of slope movement as well as the failure mechanism. The simulation results demonstrate that different infiltration schemes can lead to different deformation patterns and in turn influence the onset and propagation of failure. More evidence in the form of cracks development was also observed in the field slope during the controlled wetting test.