China was among main countries affected by the 1918 influenza pandemic, but the study of China's pandemic is very weak. Existing researches on this issue are based on flimsy historical records, which cannot reflect the whole picture of 1918 pandemic, also there are obvious misjudgments. Therefore, it is necessary to combine both Chinese and foreign newspaper reports, medical officer reports, customs materials, diaries and gazetteers in order to reconstruct the whole picture of 1918 influenza pandemic in China. Overall, China experienced two waves of influenza in spring and autumn, and their transmission paths rely on railways, waterways and post road systems. In this case, central cities such as Beijing, Tianjin, Shanghai and Hankou are the centers of the spread of the epidemic to the outside world, while other major cities along the line are the regional center for the spread of the epidemic. The first wave of the influenza spread from north to south, and spread rapidly through railway lines, through which the epidemic area was strung into lines. Later, the inland waterways and post road system woven the epidemic area from the line into a net. Fortunately, the first wave of outbreaks did not spread to areas beyond Chongqing, and is relatively mild. However, it caused public attention because of "new" and "peculiar" symptoms. In contrast, the second wave spread from south to north, and the scope far exceeded that of the first wave, even reaching inland provinces such as Yunnan, Gansu and Xinjiang. At the same time, the mortality of second wave was far beyond the first wave, many deaths have been reported in various provinces, especially the influenza in rural areas is far greater than that in city. On the whole, the conservative estimate of the number of deaths caused by the second wave is at least 3.6-4.5 million. Meanwhile, domestic and foreign situations such as the civil war, banditry, Russian revolution and Japanese expeditionary army also add complexity to the spread of influenza. Taking international factors into consideration, the Russian revolution is closely related to the spread of the epidemic in Heilongjiang and Xinjiang, and the military mobilization of the Japanese army is a key factor in the spread of the epidemic in northeast China, while the transnational trade network between China, Vietnam and Myanmar is the main channel for the epidemic to enter Yunnan province. In terms of domestic factors, the civil war and banditry have aggravated social unrest, and greatly increased the frequency of population movement in Hunan, Hubei, Shanxi and Shandong provinces, thereby increasing the speed and scope of the epidemic. The paper focuses on the issue of the spread of the pandemic influenza in China in 1918, especially focuses on the complex effects of various changing domestic and foreign factors on the spread of the pandemic. It discusses in detail the routes of the two waves of 1918 influenza in China, re-evaluating the scope and severity of the pandemic, and reconstructs a relatively complete picture of the spread of 1918 influenza in China.