Vegetation is an important indicator of surface ecosystems, and plays an important role in energy exchange, water cycle, carbon cycle, biogeochemical cycle and maintenance. Among many environmental factors, precipitation is the main climatic factor that affects vegetation changes. Studying the relationship between Normalized Difference Vegetation Index (NDVI), which can reflect vegetation coverage, and precipitation has important meaning and value. In this study, the Mann-Kendall trend test and Hurst exponent were used to analyze the change trend of the NDVI in the Loess Plateau region. The relative development rate (RDR) exponent and the center of gravity shift model were used to analyze the spatial and temporal differences in NDVI changes in the Loess Plateau region. A change-point diagnosis method of the relationship between NDVI and precipitation based on the coupling coordination degree and Petttt test method were constructed, and the change-point of the relationship between NDVI and precipitation in the Loess Plateau area was identified. The impact of precipitation on the change of NDVI and the reason for the change in the relationship between NDVI and precipitation were discussed. The results showed that:(1) NDVI in 73.49% area of the Loess Plateau showed a significant increase from 1998 to 2017(P<0.05), and NDVI will continue to increase in most areas in the future. (2) The increase in NDVI in the hilly and gully areas of the Loess Plateau was greater than that of the overall increase in the Loess Plateau. However, the increase of NDVI in the northern sandstorm area, agricultural irrigation area, and the border area of the Loess Plateau lagged behind the overall regional change. (3) The coupling coordination degree between NDVI and precipitation was increasing year by year, and the coupling coordination degree between NDVI and precipitation had a change-point significantly in 2006(P<0.05). (4) Precipitation in significant increase areas of NDVI was higher than precipitation in non-significant increase areas of NDVI(P<0.05). Precipitation had a certain effect on NDVI changes. There was a significant positive correlation between NDVI and precipitation in hilly and gully areas, northern and eastern valleys of plateau gully areas, and northern soil and rocky mountainous areas(P<0.05). However, precipitation in most areas of the Loess Plateau did not had a significant change trend(P>0.05). The main reason for the significant change-point between NDVI and precipitation in 2006 should be human activities(P<0.05). Significant change-point in the overall NDVI of the Loess Plateau were 7 years behind the implementation of the policy of returning farmland to forests in the Loess Plateau(P<0.05), and vegetation restoration required a longer period of time. The results help to further understand the interaction of vegetation changes and precipitation on the Loess Plateau, and provide a certain scientific support for ecological construction and soil erosion control in the Loess Plateau.