nowadays electromagnetics problems are analyzed and simulated with different methods. the tendency toward numerical methods has been increased, because of the limitation of analytical methods. these approaches can be used in various problems and have a lot of applications. there are some approaches that are the combination of analytical and numerical methods. one of them is the Generalized Multipole Technique (GMT). for each domain, in this semi-analytical technique, an expansion of basis functions is needed in which the coefficients of them are unknowns of the problem. each function can be used as a base to expand the fields if it satisfies the Maxwell and Helmholtz equation. with the use of these analytical functions, the unknown coefficients should be evaluated on the boundaries. different works have been done due to different kinds of functions such as spherical waves, dipoles, Gabor functions, and so on. One of these methods, which is significantly more advanced than other GMT methods and answers a wide range of electromagnetic problems is the Multiple Multipole Method (MMP). This method is more popular due to the existence of computer codes. The most important feature of GMT methods compared to other numerical methods is that there is no need to discrete the whole environment and only the borders should be discrete, so this method has a very highs speed. In this thesis, after a brief review of the GMT background, the MMP method is introduced. Then in one chapter, the MMP code for the scattering problems of the conductive cylinder, dielectric cylinder, and conductive cylinder with the dielectric coating is implemented and its response will be compared with the response of the analytical method. Finally, the two microwave structures of the post-filter and the power-divider in the rectangular waveguide and SIW technology will be analyzed using the MMP method. Generalized Multipole Technique, GMT, Multiple Multipole Method, MMP, Semi-analytic numerical methods, Computational E lectromagnetic