To research the “knee” region of cosmic ray energy spectrum, we should clearly discriminate components of cosmic rays at the knee. EN-detectors (Electron-Neutron Detector) can detect both electrons near the shower core and thermal neutrons generated in ground by EAS hadrons. As hadrons are the "skeleton" of EAS and possess the information about it, so that the electronneutron detector array has capability of primary components separation and energy measurement. At present, a cluster (16 EN-detectors) is running at the Yangbajing Cosmic Ray Observatory in Tibet to test performance at high altitude (4300 m above sea level). With a period of stably operating at Yangbajing, we demonstrated the efficiency of thermal neutron detection is affected by environmental water— drier the weather, higher the efficiency. The difference between rain season and dry season could be about 10 percent. Besides, the four EN-detectors at Tibet University so called P-TU keep running and recorded an increase in counting rate during the Naqu earthquake.