Six degrees of freedom electromagnetic tracking system is widely used in virtual reality, medical navigation and other fields. In this paper, the principle of electromagnetic tracking system and the electromagnetic theory of the transmitter coil are discussed; the magnetic dipole model of a square coil is established; the relative error between the actual coil and magnetic dipole models is analyzed. Also, a new transmitting and receiving program, driven by square wave, is presented after DC and AC electromagnetic tracking systems being compared; then structure of the said system is introduced in detail. Finally, multiple sets of data are collected to validate the program feasibly.