The methods of electromagnetic sensor with fiber grating based on the polarized effect were discussed. The effect of the linear birefringence and the incident polarizing angle on the output performance of the sensor were derived using Jones matrix and the simulations were made. The research on the relationship between the sensitivity of the sensor to the linear birefringence and the incident polarizing angle has been made. The results show that when incident polarizing angle has some special values the sensitivity of the system to the linear birefringence will be minimized and the stability of the system will be enhanced.