Disclosed is a product quality test in a winding step of the entire manufacturing process of a deflection yoke, which is a core part of a display device employing a cathode ray tube such as a color TV or a monitor, and in particular, a winding zig for measuring magnetic fields of a deflection yoke and a magnetic field measuring system of a deflection yoke using the winding zig. The winding zig and the system according to the invention include a plurality of magnetic field sensors mounted inside of the A-shaped winding zig, a digital signal generator for receiving output signals from the magnetic field sensors that sense magnetic field characteristics of a deflection coil wound around the A-shaped winding zig, amplifying the received signals, and converting the amplified signals to digital signals, a digital signal interface for converting the data outputted from the digital signal generator to serial data, and a transmitter for receiving signals processed as serial data by the digital signal interface, and transmitting the received signals.