Quality control of green sand is an important question for discussion in the domain of foundry all the while. Based on the optimizing direct-control idea, the authors have developed a control system, which form is from testing composition to adjusting composition. Base of the control system is a new method, Double Power Source Exciting Method (DPSEM), in which active clay content and moisture of green sand can be tested on-line. In DPSEM, conductivity characteristics of,green sand in alternating and direct electric fields are used as information parameters, and through appropriate transforms, active clay content and moisture can be calculated. In order to ensure of high solving precision and adaptivity of the method, artificial neutral network (ANN) is introduced into modeling. In the paper, topology, algorithm and application, effect of the new method are discussed in details.