In the big data era, data of population migration on the Internet has exerted great influence on conducting researches on the patterns of inter-regional population inflows and outflows. This study, based on Tencent's daily migration data (2015-2018), analyzed and explored the patterns of population inflows and outflows in the Qinghai-Tibet Plateau by means of methods like time series analysis, social networks analysis and space-time statistical analysis, and discussed the seasonal law of the fluid population between the study area and other cities in China and the network features of population interaction. The results indicated that: (1) The population flow in the Qinghai-Tibet Plateau was featured by seasonal variability, which could be represented as four seasons "Low, Medium, Mid-High, High" during the year. From 2015 to 2018, the Qinghai-Tibet Plateau in the interaction network of national urban floating population witnessed an increasing status. The population flow rate improved by 8.2%, and the ranking on the population mobility network increased by 24.5%. Relative to the Low season, the average daily population movements in the Medium season, Mid-High season and High season increased by 14.2%, 26.7% and 57.8%, respectively. (2) The population flow direction lied in the 45° fan-shaped range from NEE-67.5° to SEE-112.5°, and the Qinghai-Tibet Plateau had strong and frequent interactions with the capitals of the surrounding provinces. (3) Most cities across the country attached importance to a continual increase of the intensity of population interaction with the Qinghai-Tibet Plateau, and tourism had played a dominant role in promoting the changing and development. The Hotan and Bayin prefectures in Xinjiang, Chongqing, Guang'an and Meishan in Sichuan, and Sanmenxia in Henan presented a pattern of seasonal rise in the Medium and Mid-High seasons and a pattern of seasonal fall in the High season, reflecting the seasonality of labor export to the Qinghai-Tibet Plateau. In addition, population flow in cities like Turpan, Dongguan and Yuncheng showed a declining trend in the stage of High season as a result of the goods and materials supply relations.