Abstract: The environment safety problems resulted from the operation of high energy proton accelerator are described based on the analysis of radiation safety for a 235 MeV proton accelerator therapy system in the paper. The primary environmental impact resulted from the operation of high energy proton accelerator is as follows: 1)radiation dose from neutron and γ-ray to men; 2) the activation of air; 3) the activation of component cooling water of accelerator; 4) the activation of soil ( and groundwater ); 5) the activation of material of accelerator components; 6) producing harmful gases ( such as O_(3),NO_(2) and HNO_(3)). The calculated results show that the safety of men around the accelerator can be ensured during high energy proton accelerator therapy system operation, so long as it has fine design and construction for shield system, and ventilation system, and safety interlock system which it is used to protect person going incidentally into the high radiation area.