Objective To investigate changes in plantar pressure distributions on forefoot and hindfoot region during the support phase under different Achilles tensile loads. Methods Six fresh frozen human below-knee specimens were used and placed on the material testing machine. The ankles were kept in neutral position and the axial load of 350 N was applied on the specimens. Achilles tensile loads varied from 0 kg to 80 kg (0, 100, 200, 300, 400, 500, 600, 700, 800 N）were applied by weights. Two scales were placed under the forefoot and hindfoot region of the specimen, respectively, to record the pressure under the Achilles tensile loads. Results With the Increasing Achilles tensile force, the pressure on forefoot region was increasing, while the pressure on the hindfoot was decreasing. The percentage of average plantar pressure in forefoot and hindfoot region over the total plantar pressures presented a linear relationship with the Achilles tensile force (P<0.01, R2=0.996). Conclusions The support phase of foot in vitro was simulated and the plantar pressure distributions on forefoot and hindfoot region was investigated in this paper. The result can provide theoretical evidences for some diseases (such as diabetic foot ulcers, metatarsalgia) caused by plantar pressure changes due to Achilles tensile contracture in clinic.