A system and a method for estimating the mechanical behavior of human lower limbs is provided. The method includes the following steps: sensing a plurality of foot pressure signals of a user by using a sensor array, the foot pressure signals comprising at least a rearfoot pressure signal and at least a forefoot pressure signal; calculating a temporal sequence of a gait cycle of the user according to the foot pressure signals; calculating a foot reaction force of the user according to the foot pressure signals and a calibration parameter; and calculating a mechanical state of the lower limb joints of the user according to the temporal sequence of the gait cycle and the foot reaction force.