Ten-year observational data for the brown plant hopper (BPH), Nilaparvata lugens (Stål) at six plant-protection monitoring stations in Yunnan Province are presented to determine the sources of BPH, at the time of their early immigration into the rice-planting areas of Southwestern China, in April and May from 2007 to 2016. The six stations included in the study were Mangshi, Menghai,Jiangcheng, Shizong, Malipo, and Guangnan. These observational analyses were then used to provide scientific evidence in support of the migration predictions for BPH and measures for its prevention. The Flexible Particle Dispersion (Flexpart) model driven by the Weather Research and Forecast Model (WRF) outputs was used to simulate the early immigration peaks observed at these stations in 2013, 2015, and 2016 and then identify their sources. A detailed analysis of the data obtained for 2013 was conducted to determine the atmospheric dynamics, temperature, and relative humidity conditions during the early immigration of BPH in Yunnan Province. The BPH that had early immigration in Yunnan Province in these years were mainly from Myanmar, partly from Laos and Thailand, a few from Vietnam, and very few from Bangladesh. The prevailing (average) migration heights of BPH at 2216 m (2167 m) and 2489 m (2454 m) corresponded to the release heights of 1500 m and 2000 m, respectively. Good agreement between the model backward trajectories and the BPH migrating heights indicates that the model was able to capture the impact of systematic vertical airflows and the complex underlying surface on group migrations. A typical case study of an immigration event of BPH observed in Menghai, Malipo, and Guangnan in Yunnan Province from May 22nd to 26th in 2013 further demonstrates that the immigration of BPH from abroad at upper levels into Yunnan Province was mainly driven by the southwest prevailing winds associated with the Indo-Burma low pressure system; the low-temperature zone was a barrier preventing continuous northward migration over the Northeast landing areas of the BPH; and the BPH migration behaviors were highly associated with vertical motions. While the updraft was responsible for the taking-off and moving out, the downdrafts corresponded to BPH descent; the dragging effect of subsidence associated with weak rainfall was favorable this descent, whereas the relative humidity field had limited impact on the migration of BPH populations during this event.