Abstract: To explore the ecological effects of the rapid urbanization in Xiong'an New Area, an improved remote sensing ecological index (ARSEI) was constructed from five dimensions: greenness, temperature, humidity, dryness and aerosol optical depth, with 12 surrounding counties and districts as references. The changes in ecological quality and urbanization process before and after the construction of Xiong'an New Area were analyzed, and the ecological effects of rapid urbanization were evaluated. The results show that: (1) In terms of ecological quality changes, before the construction of Xiong'an New Area (2017), the ecological quality of Xiong'an New Area and its surrounding counties and districts steadily improved, with the average ARSEI increasing from 0.606 and 0.572 to 0.628 respectively. After the construction of Xiong'an New Area, the ecological quality changes showed a trend of first decreasing and then increasing. The average ARSEI decreased to 0.595 in 2020 and recovered to 0.622 in 2023, while the ecological quality of the surrounding counties and districts remained relatively stable. (2) In terms of urbanization process, before the construction of Xiong'an New Area, its urbanization speed was significantly lower than that of the surrounding areas, with the total intensity of night lights being only 51.2% of that of the surrounding areas. After that, the total intensity of night lights was 176.7% of that of the surrounding areas. The average annual increase rate of construction land area in Xiong'an New Area slowed down, from 8.7% (the same as that of the surrounding counties and districts) before 2017 to 5.1% (1.43 times that of the surrounding counties and districts) after 2017. (3) Based on the geographical detector analysis, the q values of land use in 2013 and 2023 were the largest, reaching 0.275 6 and 0.495 6 respectively, becoming the dominant factors affecting the ecological quality of Xiong'an New Area. (4) Before 2017, the ecological quality of Xiong'an New Area was better than that of the surrounding counties and districts. After that, compared with the surrounding areas, Xiong'an New Area entered a stage of rapid urbanization development, and its ecological quality experienced significant fluctuations and changes. On the one hand, large-scale urban infrastructure construction led to a sharp decline in its ecological quality. On the other hand, the positive ecological effects of the "Millennium Green Forest" project began to show in the middle of the construction of Xiong'an New Area, and the gap with the surrounding areas became smaller and smaller.