Traditional eddy current testing technology generate a magnetic field excitation by a cylindrical excitation coil, and collect magnetic field perturbations through the detecting coil, however, the magnetic field generated by excitation coil is much stronger than those generated by defect, so the defect detection sensitivity of the sensor with this structure is not high, and it is necessary to adopt difference methods to obtain the information of defect. A new type of eddy current sensor is proposed, which can be used to change the spatial distribution of the excitation magnetic field by using the rectangular excitation coil, so that the defect can be quantified without difference. Based on the analysis of the principle of the new sensor, the sensitivity difference between the traditional sensor and the defect detection is analyzed by simulation. The sensor size and excitation frequency were optimized, and the quantitative detection ability of the new sensor was verified. Simulation results show that the new sensor has high detection sensitivity and defect quantitative accuracy. To lay the foundation for the research of single excitation and multi detector array eddy current sensor.