Abstract: Based on the remote sensing image data of Mount Tai Provincial Nature Reserve 2017~2021,the improved remote sensing ecological index(RSEI) constructed by NDVI,WET,NDBSI and LST was calculated by principal component analysis. The ecological environment quality of Mount Tai Provincial Nature Reserve from 2017 to 2021 was evaluated and monitored. The results showed that:RSEI could indicate the eco-environmental quality of Mount Tai Provincial Nature Reserve better, NDVI has the greatest influence on eco-environmental quality; from 2017 to 2021,the mean value of RSEI in Mount Tai Provincial Nature Reserve increased from 0.5665to 0.5965, displayed the tendency declining at the begining and rising up in late, and the overall ecological quality showed a trend of improvement. The research results will provide theoretical basis and scientific basis for the ecological environment protection of Mount Tai Provincial Nature Reserve.