In this paper, a new amplitude quantitation synthesis method for ultralow sidelobe phased arrays is proposed, which is based on the constrained nonlinear optiedation algorithm. By introducing a set of critical constraint conditions into the optimization model, we can directly quantize the amplitude distribution instead of replacing it with a continuous equivalent aperture antenna. The mutual coupling and the element patterns are also considered in the quantization synthesis. Finally, some array simulation results are given to show the effectiveness of the method. In this paper, a new amplitude quantitation synthesis method for ultralow sidelobe phased arrays is proposed, which is based on the constrained nonlinear optiedation algorithm. By introducing a set of critical constraint conditions into the optimization model, we can directly quantize the amplitude distribution instead of The mutual coupling and the element patterns are also considered in the quantization synthesis. Finally, some array simulation results are to to show the effectiveness of the method.