Supported by GIS and RS technology and combined with field investigation and other accessory data, the authors evaluated the ecological environment quality of Beijing by using remote sense images of TM, SPOT4, QUICKBIRD and the Ecological Environment Quality Evaluation Criteria. The monitored variations of Beijing’s ecological environment from 2000 to 2006 were also analyzed. The results show that the ecological environment quality evaluation index of 2006 was 59.707, remaining in the rank of “fine”. From 2000 to 2006, the ecological environment was steadily in the rank of “fine”. Nevertheless, the area of plantation was decreased by 339.09 km2, the area of town building was increased by 285.24km2 and the area of water was declined by 118.98 km2, which may be attributed to such factors as reduction of rainfall, urbanization and human activity.