To make a MRI system portable, a practical approach is applying Halbach magnet array and nonlinear spatial encoding strategy. Here, the rotation of a magnet array for imaging is replaced by electrically forming RF receive coil aggregates with phase delay. For the resultant system with a new encoding matrix, Truncated-Singular-Value-Decomposition with an optimal regularization parameter is proposed which reconstructs images with good quality. An accelerated L-curve method is proposed to obtain the optimal regularization parameter. Results show that the proposed strategy provides considerable improvement of the image quality compared to existing method, e.g. Kaczmarz iteration, without rotating the magnet array.