A simulating circuit for simulating the operation of a magnetic tunnel junction (MTJ) device having at least a free layer and a fixed layer is provided. The simulating circuit includes a closed switch loop for simulating the magnetization of the free layer and the fixed layer, thus for simulating the data recording, wherein the magnetization includes parallel state or anti-parallel state; a first write loop for simulating the first quadrant of the operation region of the MTJ device; a second write loop, a third write loop, and a fourth write loop for simulating the second quadrant, the third quadrant, and the fourth quadrant of the operation regions, respectively; a first resistor for simulating the wire resistance of the bit lines; a second resistor for simulating the wire resistance of the write word lines; and a third resistor for simulating the resistance of the magnetic MTJ device.