Laser thermography is a new method to detect micro cracks in inductors, but the proximity of inductors in batch automatic detection made it easy to cause positioning errors and false detection results. According to the analysis of image features in the process of laser scanning and thermal imaging detection, a new method was proposed to obtain the temperature gradient map and eliminate its excitation nonuniformity by using the sub maximum filter, and to disconnect the adhesion of samples and remove the interference noise points by using morphological operation. The inductance images were segmented combining distance transformation with watershed algorithm. The experimental results show that the method realizes the automatic separation and extraction of ferrite inductor from image, which lays a good foundation for the separation of ferrite inductors.