For superlong singletube singletrack railway tunnels in extremelycold highplateau area, worldlevel technological challenges in surveying and alignment selection, construction method selection, longdistance deadend ventilation, deep vertical shaft sinking, ecologicallyfragile environment protection and tunneling in lowoxygen environment are faced. In the paper, the design of superlong Dangjinshan tunnel on DunhuangGolmud railway is presented. Dangjinshan tunnel has the following characteristics: 1) high altitude, high ground stress and high seismic intensity; 2) low temperature and low atmospheric pressure; 3) long singledirection slope, longdistance deadend ventilation and longdistance antislope water releasing; 4) lots of fractured zones and lots of adverse geological units; 5) deep cover and serious water inflow. Comparison and contrast is made among three construction methods considered for the tunnel, i.e., drill and blast method, TBM method and “drill and blast + TBM” method, in terms of economy and technology, and drill and blast method assisted by heavyduty construction equipment and machinery is proposed for the tunnel. Finally, the following advice is made on the design and construction of superlong singletrack railway tunnels: 1) More attention should be paid to the geophysical prospecting technology in the selection of the alignment of superlong tunnels; 2) The relationship between the survey and the design should be well dealt with; 3) Mechanized construction should be adopted for superlong tunnels in highplateau area; 4) The function of the parallel service gallery should be fully used; 5) More attention should be paid to the design of the environment protection measures. 