The specific impact of ecological environment quality at a regional scale due to the rubber plantations expansion is still unclear in Xishuangbanna, Yunnan province, China. First, we used a pixel and phenology-based multiple normalization approach to map rubber plantations over six time periods during 1995–2018 with the available high-quality Landsat imagery. Second, a pixel-based optimized algorithm was developed to reduce the commission and omission errors of the rubber plantations maps and we mapped the rubber plantations expansion area. Third, a remote sensing-based ecological index (RSEI) was employed to assess the rubber plantations expansion area ecological environment quality. RSEI value decreased with the lowest value in 2007 (0.511) and increased with the highest value in 2016 (0.727). This study demonstrated that the ecological environment quality degraded from 1995 to 2007 with an increase of rubber plantations expansion, but improved gradually from 2007 to 2018 with the slow growth of rubber.