The invasive pest fall armyworm (FAW) has posed significant threats to Chinese agriculture since first reported in 2019, but it is still unclear exactly how the magnitude and distribution of threats vary between Chinese provinces. Here, we calculated the total potential cost of FAW to each of 31 Chinese provinces and identified the provinces posing the greatest threat to the rest of China. We found that (1) only 16.1% and 25.8% of provinces remained at upper and lower levels of potential threats (PT_p), respectively. (2) The total potential costs (TPC_p) of four provinces including Yunnan (830.51 M$), Guangxi (346.09 M$), Sichuan (116.87 M$), and Shandong (116.43 M$) were more than 100 M$. Six of the top 10 provinces exhibiting the highest TPC_p were also among the top 10 agricultural producers. (3) Nine of the top 10 provinces with the largest TPC_p values relative to regional GDP were underdeveloped provinces ranking bottom 15 in regional GDP. (4) Based on the total invasion cost (TIC_s), the underdeveloped provinces Yunnan (233.31 M$) and Guangxi (218.44 M$) ranked first and second as potential source provinces. Overall, larger agricultural producers might be more at risk and could suffer a bigger absolute loss from the further FAW threat. Underdeveloped provinces might be more vulnerable to FAW in relative terms and more likely to be a major FAW source. Our study suggests considerable scope for ongoing FAW redistribution by summarizing its threat to Chinese agriculture on a province-by-province basis and thus highlights the need for cross-provincial cooperation and national coordination to slow its spread.