The present invention relates to a walking assistance device with detection function, which includes a movable frame, a power transmission device mounted under the frame, a detachable power unit mounted on the frame, at least one signal transmitter and at least one signal receiver for detecting the distances from a first portion and a second portion on the user's body to a correspond position of the frame respectively. According to the distances detected, a control unit sends signals to the power transmission device to maintain the distance between the user and the frame within a preset range, therefore to provide supporting forces when the user needs.