In order to improve the automation degree of the triband AEM system, the author designed an electromagnetic compensation unit based on the fuzzy control and linear incremental control approach so as to complete the highprecision, high stability, and large dynamic range Em compensation. With the real and imaginary components of the electromagnetic field output by the airborne electromagnetic receiver as the control input parameters, the compensation current in the compensation coil as the control object, the 80C52 monolithic processor as the control chip, the author adopted FFSI inference program to implement the fuzzy control of the compensation quantity, so as to realize the real time program control of the linear field and the voxtex field. The experimental data show that the control system can quickly achieve the realtime compensation with high stability and noise level.