Abstract: Open-pit coal mining in China has developed rapidly due to its obvious advantages over underground mining. However, since most of the open-pit coal mining areas are located in ecologically fragile areas such as Inner Mongolia, Xinjiang and otherareas, open-pit mining has caused great impact and damage to the local ecological environment. Taking Shenbei-Shengli No.1 open-pit coal mine as an example, it is a large-scale open-pit coal mine located in grassland ecological environmental area. Its development has a great impact on the ecological environment of the mining area. To evaluate the degree of open-pit mining impact on the ecological environment of the mining area, an open-pit coal mine is proposed. The evaluation method of greenness is to establish the evaluation index system, evaluation model and evaluation standard of the ecological environment of the mining area, and to quantify the evaluation index of Shengli No.1 open pit mine, and carry out the evaluation of the comprehensive “greenness” index of open pit mine. The results show that the comprehensive greenness index of No.1 Shengli open-pit coal mine is 0.707, which meets the “good” standard. It scores relatively high for the existing large-scale open-pit coal mines in China. In the first grade index of Shengli No.1 open pit coal mine, the “solid environment”and “ecological environment”scores are low, which is the weak link of the open-pit coal mine ecological environment. Among the secondary indicators, “land occupation index”, the “mining area topographic condition index”, the “pollution control and waste utilization index”and “ecological resources reconstruction protection and utilization index” scored lower, and technical and management measures to improve their scores were put forward. Through the analysis of the “water environment”and “atmospheric environment”,15 three-level indicators with lower scores were obtained,and improvement measures were proposed for 10 of them. The other five indicators were caused by objective factors.