Well track control is important in drilling deep well and directional well. The electromagnetic measurement while drilling system can monitor and transmit the state parameters of borehole to ground device by wireless electromagnetic wave. This system is applied widely for its high transmission rate and getting none influence from drilling fluid. The paper elaborates a self-developed electromagnetic measurement while drilling system in China and its test situation, which can receive signal up to 200mV from borehole of 609m in depth. The experimental research shows that this system is reliable and can satisfy the requirement of the annulus pressure, temperature and other parameters near the bit.