Abstract: In order to study the spatio-temporal changes on ecological environment and influence factors of the lower reaches of Luanhe river, we collected the remote sensing image(1985—2015) and other ancillary data, and used supervised classification method to extract the dynamic change of ecological factors.The result show that:1) farmlands dominated in 1985, 1990, 1995, 2000, 2005, 2010, and 2015 covering about 1530.59km², 1388.88km², 1388.15km², 1121.88km², 1166.48km², 1017.07km² and 883.15km² respectively, although farmland has been in a downward trend.2) From 1985 to 2015, the forest area and grass land has shown a rising trend, the rising rate of forest is 15.78km² every five years, the rising rate of grass land is 9.23km² every five years.3) The cultivated land area change is in a rapid decline trend in nearly 30 years, decline rate is 103.8km² every five years.The building land area in 2015 is about three times of 1985, increase rate is 83.00km² for every five years.The water area is in decline too, decline rate is 4.11km² every five years.4) Expansion of cities and towns are the main factors influencing the ecological environment of the lower reaches of Luanhe river.

Key words: the lower reaches of Luanhe River, ecological environment, spatio-temporal changes