A magnetic analyzer was designed to measure the energy spectrum of the pulsed intense electron beam of a linear induction accelerator. The principle of magnetic analyzer was described. The basic parameters were set based on the accelerator and some test conditions. The magnet was designed theoretically according to these parameters. 3-D simulation and optimization of this design were performed using Opera/Tosca software from Vector Fields Co. The final parameters of this magnetic analyzer were obtained. The magnetic analyzer was C-shape, with the bending radius of 300 mm and the bending angle of 60 degree after hard-edge approximation, and the good-field-region was 6.54 cm. Results of the design satisfy the physical requirement very well.