Objective To analyze plantar pressure features of patients in injured and healthy sides of the lower limbs under different walking conditions after the trimalleolar fracture surgery, and compare these characteristics with healthy subjects. Methods Twelve Trimalleolar fracture patients and twenty-three healthy subjects were recruited and their plantar pressure characteristics under different walking conditions were tested, including peak pressure, contact area and contact time percentage. Results Comparison between injured and healthy sides: during level walking, peak pressure of the 3rd-5th toe in the injured feet were smaller than those in the healthy sides; in inversion position, peak pressure and contact area of the 3rd-5th toe area in the injured feet were smaller than those in the healthy side; in eversion position, peak pressure, contact area and contact time of the 3rd-5th toe in the injured feet were smaller than those in the healthy sides, and peak pressures of the hindfoot area were larger than those in the healthy sides. Comparison between patients and healthy subjects: under three kinds of walking conditions, peak pressures of the 2nd and 3rd metatarsus bones, the 2nd toe, the 3rd-5th toe, contact area of the 1st-5th toe and contact time percentage of the 2nd toe, the 3rd-5th toe area were all smaller than those of healthy subjects, while contact time of the hindfoot and mid-foot area were all smaller than those of healthy subjects. Conclusions The plantar pressure characteristics of Trimalleolar fracture patients were asymmetrical. Compared with healthy subjects, the plantar pressure features of patients were abnormal during stance phase. Compared with healthy subjects, the motor control ability and stability of patients in eversion positions were decreased. The plantar pressure characteristics at ankle eversion can be used to evaluate ankle joint function.