[Objective] This study aimed to investigate the phenology of vegetation, i.e., the seasonal changes in the growth and development of vegetation in the Loess Plateau region of Gansu Province, and to gain a deeper understanding of how climate change affects the growth patterns of vegetation in this area. [Methods] Based on MODIS NDVI datasets, meteorological data, digital elevation models（DEM）, and standardized precipitation evapotranspiration index（SPEI） data from 2002 to 2021, the start of the growing season（SOS）, end of the growing season（EOS）, and length of the growing season（LOS） of vegetation in the Loess Plateau region of Gansu Province were extracted. Theil-Sen trend analysis and Mann-Kendall tests were used to explore the spatiotemporal dynamics of SOS, EOS and LOS. Partial correlation analysis was employed to investigate the relationships between vegetation phenology and temperature, precipitation, drought, and topography. The Hurst index and random forest regression model were utilized to predict future changes in vegetation phenology in the Loess Plateau region of Gansu. [Results] 1) The SOS of vegetation in the Loess Plateau region of Gansu was concentrated between day 81 to 138, with a change rate of-4.5 d/10 a; the EOS was concentrated around day 266 to 305, with a change rate of-0.4 d/10 a; and the LOS was concentrated around 131 to 218 days, with change rate of 2.6 d/10 a. 2) During the study period, temperature was positively correlated with SOS（90%） and EOS（54%）, and negatively correlated with LOS. Precipitation was positively correlated with SOS（85%）, and negatively correlated with EOS（57%） and LOS. SOS in the western part of the Longxi Loess Plateau and EOS in the southern part of Tianshui were significantly negatively correlated with drought, while LOS in some areas such as Lanzhou, Linxia and Dingxi was significantly positively correlated with drought. 3) In the future, in the southern part of the Loess Plateau region of Gansu, SOS is expected to advance, EOS is expected to delay, and LOS is expected to extend; in the northern part, SOS is expected to delay, EOS is expected to advance, and LOS is expected to shorten. [Conclusion] From 2002 to 2021, due to significant influences of meteorological factors, the growth cycle of vegetation in the Loess Plateau region of Gansu has effectively lengthened, and has improved the local ecological environment and promoted the stability and sustainable development of the ecosystem. In the future, efforts should be made to further strengthen ecological environment protection, promote in-depth ecological restoration and governance, and make greater contributions to the construction of ecological civilization in the Loess Plateau region of Gansu.