[Purpose] The aim of this study was to evaluate the structural deformity of the foot joint on the affected side in hemiplegic patients to examine factors that affect this kind of structural deformity. [Subjects and Methods] Thirty-one hemiplegic patients and 32 normal adults participated. The foot posture index (FPI) was used to examine the shape of the foot, the modified Ashworth scale test was used to examine the degree of ankle joint rigidity, the navicular drop test was used to investigate the degree of navicular change, and the resting calcaneal stance position test was used to identify location change of the heel bone. [Results] The FPIs of the paretic side of the hemiplegic patients, the non-paretic side of the hemiplegic patients, and normal participants were −0.25 ± 2.1, 1.74 ± 2.3, and 2.12 ± 3.4 respectively. [Conclusion] Our findings indicated that in stroke-related hemiplegic patients, the more severe the spasticity, the more supinated the foot. Further, the smaller the degree of change in the navicular height of hemiplegic patients is, the more supinated the paretic side foot is. Additionally, a greater change in the location of the calcaneus was associated with greater supination of the overall foot.