Winding deformation is one common faulty and hidden danger in the normal operation of power transformer. It is good for ensuring power system safety and reliably operation by diagnosing the winding deformation condition of power transformer. This article designed and developed a transformer winding deformation synthetically detecting instrument, which has two measurement theories, Frequency Response Method and Low Voltage Reactance Method. This instrument is not merely to completely satisfy the technical requirement of frequency response method and low Voltage reactance method, but also to have a portable structure and simply operation. It can be very convenient to effectively detect and synthetically diagnose the running condition of power transformer windings on site.