Abstract: When the beam is injected to the storage ring, the beam loss will influence the radiation field of beam injection zone and radiation protection zone. Using the beam loss monitoring (BLM) system to study the location and rate of beam loss, the results showed significant loss of beam in the injection zone and its downstream position. By the Monte Carlo simulation and experiment, the energy spectra of neutron and photon and their dose rates were obtained. When the beam is lost at the magnet,the peak of evaporation neutron spectrum is 0.9 MeV and direct emission neutron are not obvious. When the beam is lost at the vacuum tube,the peak of evaporation neutron and direct emission neutron are 4 MeV and 20 MeV, respectively. The energies of photons are mainly below 5 MeV. The dose rates of neutron and photon are at the same level. The dose rate during the injection is about two orders of magnitude higher than that without injection. The dose rate of photon in whole stage of electron positron collision experiment is about 1 000 μSv/h, which is an order of magnitude higher than neutron dose rate.

Key words: BEPCⅡ, the injection area, beam loss, neutron, photon, FLUKA