With the development of g-ray astronomy, a cosmic ray observatory was founded in the Yangbajing valley of Tibet highland (4300 m.a.s.l.) 10 years ago. Its EAS array of China-Japan ASg Collaboration detected successfully the steady emission of multi-TeV g rays from the Crab Nebula, the strong outbursts from AGN Mrk 501 in 1997 and from Mrk 421 in 2000, which is the first detections in the EAS experiments. The deviation and movement of Sun shadow by cosmic rays induced by solar and interplanetary magnetic field, has been only observed and will be adopted to monitor the variations of solar activity. Taking the advantages of high altitude and the combination of experiments of EAS array and emulsion chambers + burst detectors, the primary energy spectrum and composition of ultra-high energy cosmic ray have been studied. For exploring the 100 GeV gap region between the space and ground-based experiments, the project of China-Italy ARGO Collaboration is under constructing. Finally, to challenge the 5 GeV low threshold and the highly variable extragalactic sources, a high altitude huge IACT project 5@YorG in the future is discussed.