Aiming at the problem that when a single excitation AC electromagnetic probe is used to detect cracks in arbitrary direction, missing detection happens easily, a novel dual excitation sensor for detecting the oblique cracks on the surface of Austenitic stainless steels is designed. A simulation model for the detection of surface cracks of Austenitic stainless steel with alternating current field measurement is established. A metal plate surface crack detection system based on a novel double-excitation sensor and high-resolution TMR sensors was developed. Based on the theoretical model and experiment system, the influence rule of crack orientation and crack width on the magnetic field component amplitude picked up by the sensor are studied. Simulation and experiment results show that using the distortion characteristics of magnetic field components Bx, By, the tiny cracks with surface dimension of 15 mm×0. 2 mm and depth greater than 3 mm can be detected with the same sensitivity, and the determination of the crack direction can be achieved. After the width compensation parameter is introduced the determination errors of transverse and longitudinal cracks are reduced, and the maximum determination error is 3. 9°.