The Yellow River Basin is an important ecological function area in China and plays an important role in the economic and social development and the ecological security of our country. How to obtain the temporal and spatial pattern and evolution trend of ecological environment quality in the Yellow River Basin in time and accurately is of great significance to the protection and construction of ecological environment in the Yellow River Basin. In this paper, Google Earth Engine (GEE) platform was used to filter the Landsat remote sensing images of the summer (June-September) from the target year and before-after the target year. The greenness (NDVI), wetness (Wet), heat (LST) and dryness (NDSI) were calculated by removing the cloud pixels, masking the water body information, and taking the median composites. Based on this, the remote sensing based ecological index (RSEI) was established quickly through Principal Component Analysis (PCA). The results showed that:(1) the average contribution rate of NDVI, Wet, LST and NDSI on the first principal component (PC1) was 89.60%, and it was feasible to construct RSEI based on PC1 in the Yellow River Basin. (2) From 1990 to 2019, the RSEI presented two stages as a whole:rapid improvement and slow improvement. But from 1990 to 2000, the average growth trend was 0.005/a, with a growth rate of 11.69%, because the contribution from very poor to poor (101800 km²), poor to medium (56900 km²) and medium to good (70800 km²) of ecological environmental quality levels was greater. From 2000 to 2019, the average growth trend was 0.001/a, with a growth rate of 3.86% only, because the contribution from poor to very poor (61000 km²) and good to medium (40900 km²) of ecological environmental quality levels was greater. (3) From 1990 to 2019, the improvement of ecological environment quality accounted for 76.38% of the total area of the Yellow River Basin, among which the significant improvement accounted for 26.14%; the reduction of ecological environment quality accounted for 23.62% of the total area of the Yellow River Basin, among which the significant reduction accounted for 1.46% only. In the past 30 years, the ecological environment quality of the Yellow River Basin has improved as a whole. The ecological environment quality of the upper and middle reaches of the Yellow River Basin has improved the fastest, where the ecological projects have been carried out by our country. While the ecological environment quality of some national key economic development zones has deteriorated. By using the GEE platform, the temporal and spatial pattern and evolution trend of ecological environment quality in the Yellow River Basin can be obtained in time and accurately.