Abstarct: an important part of applications of nanostructured electronic devices will be in the presence of laser radiation and effective magnetic fileds .For this reason extensive efforts have been made to understand the various aspects of electron transitions in semiconductor nanostructures. in this thesis the transition between the Landau levels in a laterally confined quantum well wire in the presence of laser field is studied theoretically .The effective role of interactions between electrons and longitudinal optical phonons which is very useful in the investigation of the relaxation of charge carriers in the nanostructures is considered .the energy spiliting due to the electron phonon interaction in the system is studied as a function of the applied magnetic and laser field by performing numerical calculations .results show that in a higher magnetic field and intense laser field the energy spiliting due to the electron phonon interaction decreases.