Abstract: The Five-hundred-meter Aperture Spherical radio Telescope (FAST) is located in the remote area of Qiannan prefecture in Guizhou province. The largest single dish radio telescope in the world is build in the karst depression. Since FAST observes very weak electromagnetic signals from distant celestial sources in the Universe with extremely high sensitivity, it is easy for FAST to receive electromagnetic interference from the telescope’s own equipments and the surrounding site. The electromagnetic interference level around the site is required to be extremely low. In order to achieve the objective of scientific observation, an important basic condition for FAST is how to keep the quiet electromagnetic environment around the telescope. Several main measures have been studied. At first, in order to protect FAST quiet electromagnetic environment, the first step to reduce the radio interference is to set up a radio quiet zone within a radius of 30 km with FAST site as the center. Secondly, the strict Electromagnetic Compatibility requirements of telescope itself and its surrounding electronic and electrical equipments are required to prevent interferences from the telescope. Based on the effective electromagnetic compatibility design and protection measures, the radio environment of FAST station is quiet and stable. Due to the economic development in Guizhou province, especially in Qiannan prefecture, the number of construction projects around FAST site has increased rapidly. In the face of the coordination with many radio communication services and local economic projects, how to achieve a balance between the scientific needs and local development is the key subject for the maintenance of FAST radio quiet zone.