Abstract: MSFDCADP is completed by BASIC compiler on an IBM personal computer. The package is based on modem frequency domain method for linear multjvariable system. There are direct and inverse Nyquist array deoign technique, dyadic expansion design technique, data processing module and simulation module in the package. This paper discusses the design principle, levels construction and function. Calculation formulas of kernel algorithms are given. Finally, two design examples are used to prove the effectiveness of MSFDCADP.