Abstract: MCAD,a CAD software based on two scalar potential methods and finiteelement method is used for accelerator magnet design.The program consists ofthree parts:pre-data processor,data processor and post-data processor.Pre-dataprocessor encloses mesh automatic generation and mesh display.Data processor isbased on Newton-Raphson iteration which speeds convergence in non-linear case.Field display is available after post-data processor.Beam trace and phase shiftcould be computed also in this stage.Some examples are given in the paper.