The standardized precipitation evapotranspiration index and the standardized ecological drought index based on the entropy-weighted Euclidean distance method in the Tarim River Basin were constructed. The three-threshold run theory and Copula function were introduced to quantify the characteristics of meteorological drought propagating into ecological drought using propagation ratios and triggering thresholds, revealing the dominant driving factors. The results indicate that the frequency, duration, and intensity of ecological drought in the Tarim River Basin from 1983 to 2022 are higher than those of meteorological drought. The propagating ratio of meteorological drought propagating to ecological drought is 0.1~0.9, with a triggering threshold of -2.5~-0.05. The propagating characteristics have spatial heterogeneity, and the propagating risk decreases from near desert areas to the surrounding areas. The propagating ratio slightly increased in 80% of the Tarim River Basin, while the triggering threshold significantly increased in the southern near desert area and the northern Aksu River area (with a maximum increase rate of 1.5 per 10 a). The contribution rates of each driving factor are similar, with solar radiation (20.1%) and potential evapotranspiration (21.3%) being the dominant driving factors in regions with significant changes in propagation ratio.