Fig.1 The distribution of atmospheric neutron environment

   Near Space is the area between 20km to 100km above sea level. Recently,  more and more attention is paid to Near Space for its widely  application value. Atmospheric neutron is one of the major radiation  environments in near space, which seriously threatens the safety of  aircraft and aircrew at this region. A Monte Carlo simulation model  based on atmosphere model, cosmic rays model and geomagnetic field model  has been developed for the near space atmospheric neutron environment.  The neutron distribution which induced by cosmic rays and solar  particles have been calculated separately. Fig.1 compares our model with  QinetiQ Atmospheric Radiation Model (QARM), we can draw a conclusion  that our model is credible. The model could be applied in many fields,  such as, evaluating single event effects of microelectronics and  analyzing radiation dose of aircrew.