A completely new concept, the Air Breathing Ion Engine (ABIE), has been proposed for spacecraft drag compensation at a super low earth orbit. In order to experiment on ground test, it is necessary to simulate the atmospheric environment of there. In this study, we are simulating the environment using surface neutralization. As the atomic oxygen source, a 6 cm ion source using Electron Cyclotron Resonance (ECR) discharge was operated in changing condition inside a vacuum chamber. The atomic oxygen flux was measured by the mass change using polyimide covering QCM. We achieved a flux density of 1.5 x 1015 cm-2sec-1, which corresponded to the orbital conditions at an altitude of 220 km for the initial stage of the experiment of the ABIE. On the other hand, it was so low utilization efficiency that slow neutral particles accounted for a substantial fraction of the beam.