In the bright national speed skating hall, Wu Xiaonan, Secretary of the Party committee and chairman of Beijing national speed skating Hall Management Co., Ltd., squatted on the green cement floor with great emotion. His mind flashed the picture of "ice ribbon" from scratch, digging earthwork, laying foundation, positive and negative zero, completing the main concrete structure, building internal structure, pulling steel cable, and installing curved curtain wall system, From the appearance of "ice ribbon" at the end of 2019 to the formal power on of venue competition lighting, more than 1000 days and nights have condensed the efforts of him, his colleagues and thousands of construction workers. Wu Xiaonan is looking forward to tomorrow. At his feet, 12000 square meters of cement floor flatness error is not more than 5mm, under the cement is connected to the length of more than 120 kilometers of refrigeration pipeline. When it comes to refrigeration, the national speed skating hall will adopt carbon dioxide transcritical direct cooling ice making technology. It is also the first Winter Olympic stadium to adopt this technology. It is the crystallization of the wisdom of the Chinese people. This has played a leading role. Among the 15 pieces of ice in Beijing competition area of Beijing Winter Olympic Games, 7 pieces will use carbon dioxide technology to make ice. But it is also carbon dioxide ice making, the difficulty of the national speed skating hall is not comparable to other venues. 12000 square meters of ice making is not a simple superposition of areas, and it needs to solve problems that have not been encountered before. The ice rink structure and ice rink carbon dioxide refrigeration system also obtained the utility model patent certificate of the State Patent Office on December 11. So the challenge of realizing this huge ice surface is also huge. According to the relevant person in charge of the Beijing Organizing Committee for the Winter Olympics, through unremitting efforts, the construction of venues and infrastructure has achieved phased results. In the Beijing competition area, Shougang's ski jump platform was completed and the world cup competition of the International Snow Federation was held. The National Swimming Center completed the full ice test and held the National Youth curling open. The transformation of the existing venues such as the national gymnasium and the capital gymnasium was accelerated. In Yanqing competition area, the national alpine skiing center racing track and water supply, power supply, cableway, snow making and other supporting facilities were all completed, meeting the requirements of the test activities; the construction of the national snowmobile and sleigh center track was basically completed, and passed the site certification jointly held by the international snowmobile and international sleigh Federation at the end of October. In Zhangjiakou, the national cross-country skiing center and the national biathlon center were completed; all six tracks in Yunding skiing park were completed, and the freestyle and snowboarding U-shaped pool world cup competitions were held. All competition venues will be completed this winter and meet the test requirements. Recently, four international winter sports federations, such as the International Skating Union and the international skiing Federation, came to China and gave high praise after inspecting the main competition venues. The construction and renovation of non competition venues are also progressing steadily. All the Winter Olympic villages in the three competition areas will be capped and the international media center will be put into use in July 2021. In terms of infrastructure, Beijing Zhangjiakou high-speed railway and Beijing Lishui expressway have been open to traffic for more than a year, which has greatly facilitated people's travel. Water, electricity, municipal, communications and other supporting facilities were built simultaneously.