Abstract: A model on the interactions of relativistic electrons and magnetic field with space oscillation is put forward based on the observational characteristics of solar highenergy electrons and opened magnetic field in corona and in interplanetary medium.Numerical method is used to study R-mode cyclotron electromagnetic instability which is excited by electron beam going through longitudinal field wiih space oscillation, when some initial conditions are satisfied such as the velocity of beam and the wave number of oscillation field. The electromagnetic wave with low-frequency drift may be excited when solar high-energy electrons pass through corona and interplanetary medium.