The effect of 3 forging routes (Route A - 1~12 passes by plane forging (PF) and reverse-plane forging (R-PF), Route B – 1~6 passes by PF and R-PF, 7~12 passes by diagonal forging (DF) and reversediagonal forging (R-DF), Route C – 1~12 passes by DF and R-DF) on maximum load to produce the workpiece, deformation heterogeneity and hydrostatic pressure distribution in AA1100 was theoretically investigated using finite element analysis (FEA). The maximum load per pass required to complete 1 cycle of the SPD process was different depending on the forging routes. Route A was relatively higher than Route B and C. From the results of effective strain, the deformation heterogeneity was predicted at the center, edge, and corner regions of the AA1100 workpiece produced by Route A and B. However, the distribution of effective strain in Route C was relatively more homogeneous than Route A and B. The average hydrostatic pressure, which is closely related to the suppression of crack formation in the workpiece under multi-axial forging, was predicted to be relatively bigger in Route C than Route A and B.