The invention relates to an intermediate support overhead line sag measurement device comprising an image acquisition module, a wireless transmission module, and a hand-held control end. The image acquisition module comprises an adjustable zoom lens module, a measuring scale module, a turntable unit, a sensor module, a power module, an analog-to-digital conversion module, a motor drive module, a voltage regulator module, and a control module. The control module is connected with a 360-degree steering engine module. The adjustable zoom lens module is fixed to the 360-degree steering engine module through a U-shaped rotary bracket. The U-shaped rotary bracket is rotationally connected with the control module through the motor drive module. According to the invention, remote control is carried out through the control module and the handheld control end, observation and measurement are convenient, and the sag of a strain section needing measurement can be measured by a single person. The human cost is reduced, and operation is easy. The efficiency and precision of overhead line sag measurement can be improved effectively, and the installation efficiency and measurement precision of the sag measurement device are improved.