According to spinning projectile of rolling in dynamic environment, an intelligent attitude determination method based on magnetometers data only was proposed with consideration of cost and size. Experimental signal data were used for training samples of an artificial neural network (ANN) depending on simulating flight attitude of turntable. Pitch angle estimation was completed by ANN. Based on it, roll angle was calculated eventually. Prototype of low cost micro inertial sensors and commercial inertial navigation system were used for implementing experiments. Experimental results demonstrate that the proposed method is feasible. The proposed intelligent attitude determination method by magnetometer data only can provide accuracy of less than 1.5 degree.